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Archive 1

Referencing media articles for this article is serious folly.

I noticed that the very first reference for this article is a media article, which is a big mistake considering the history of the Gliese 581 c article that originally said that planet was habitable because the discovery team got their incorrect figures sensationalized by these media types, and it turned out when two other teams of scientists consisting of planetologist and geologists not just astronomers looked at it, both teams concluded that it was not in the habitable zone, not even close:
"...surface temperatures ranging from 700 K to 1000 K (430 to 730 °C)."
I will remove the media references if I find out they are incorrect as well.
24.78.166.69 (talk) 01:03, 30 September 2010 (UTC)

Relax a bit! Removing any references in an early article is unfriendly, but if there's errors or conflicting information in them (or here on the talk), that can be noted in the reference line. Otherwise someone else might just re-add the same wrong information! Tom Ruen (talk) 01:36, 30 September 2010 (UTC)


  • Comparison for editors not article
Star Radius: 0.29 Temperature: 3480 Irradiance %
Companion Mass ± M⊕ Semimajor axis (AU) A± Orbital period (days) P± Eccentricity Ecc.± W/m2 of Earth's
b 15.65 to 30.4 0.04 5.36874 ± 0.00019 0 9448.40 691.68%
c 5.36 to 10.4 0.07 12.9292 ± 0.0047 0.17 ± 0.07 3085.19 225.86%
g ≥ 3.1 0.14601 ± 0.00014 36.562 ± 0.052 0 709.11 61%
d 7.09 to 13.8 0.22 66.8 ± 0.14 0.38 ± 0.09 312.34 22.87%
f ≥ 7.0 0.758 ± 0.015 433 ± 13 0 26.31 1.93%
Earth - 1 1 - 365.26 - 0.0167 1366.0 100%

After all the debate about C & D being or not being habitable (turns out C is hotter than Venus not "habitable" oops, sorry, and D is colder than Mars not "Habitable" oops, sorry.), how convenient that another is found that receives 61% of the heat that the Earth does and they can play this game some more.
That is barely warmer than Mars; This new algorithm interpretation is born out of the fantasy scenario question "if Venus was at the orbit of Mars would it be habitable?" because of the GHG effect is so much stronger with Venus to make up for the distance.
Hopefully they will do the math and it can be clearly expessed the way it is now with the Gliese 581 c mention of Venus' GHG effect, +430 °C (770 °F). 24.78.166.69 (talk) 02:26, 30 September 2010 (UTC)

Good sleuthing. We'll see! Yes, hopefully there'll be some "contrary opinion" sourcing references to update the young article. It's hard to tell who's doing the real hyping, media taking the most hopeful quotes or researchers real opinions. Tom Ruen (talk) 04:18, 30 September 2010 (UTC)

This is from the main scientific source paper and I would like to turn the number data into a chart:
"Nevertheless, we estimate the equilibrium temperature given L⋆ = 0.0135L⊙ for the host star. We assume a Bond albedo for the planet of A=0.3, a typical value for objects in the inner Solar System (Earth’s Bond albedo is 0.29). For the 36.6-day planet candidate, its semi-major axis of 0.146 AU leads to an equilibrium temperature of 228 K (-45 °C). If instead the Bond albedo is assumed to be 0.5, the equilibrium temperature becomes 209 K (-64 °C). This planet candidate would thus appear to also satisfy another necessary condition for habitability, that Teq < 270 K (-3°C). An equally important consideration is the actual surface temperature Ts. The equilibrium temperature of the Earth is 255 K (-18°C), well-below the freezing point of water, but because of its atmosphere, the greenhouse effect warms the surface to a globally-averaged mean value of Ts = 288 K (15°C). If, for simplicity, we assume a greenhouse effect for GJ 581g that is as effective as that on Earth, the surface temperatures should be a factor 288/255 times higher than the equilibrium temperature. With this assumption, in the absence of tidal heating sources, the average surface temperatures on GJ 581g would be 236 – 258 K (-37°C to -15°C). Alternatively, if we assume that an Earth-like greenhouse effect would simply raise the equilibrium temperature by 33 K (33°C), similar to Earth’s greenhouse, the surface temperature would still be about the same, 242 – 261 K (-31°C to -12°C). Since it is more massive than Earth, any putative atmosphere would likely be both denser and more massive. It would be denser because of the larger surface gravity, which would tend to hold more of the atmosphere closer to the surface. And the atmosphere may be significantly more massive if we simply assume that the planet went through a formation process similar to that of the Earth and that all the bodies that went into forming GJ 581g had the same relative amount of gasses as in the bodies that went into making up the Earth. Some of these gases would subsequently be outgassed to make the atmosphere. Note however, that the amount of outgassing can depend critically on the (evolving) internal structure of the planet. More simply, the rocks that hold the gases in GJ 581g will have experienced different pressures and temperatures than those in the Earth. In turn, this determines how easily the gases would be released."

  • Steven S. Vogt et al 2010, page 31.

24.78.166.69 (talk) 06:06, 30 September 2010 (UTC)

Although I find it highly suspicious that they have a 3.1 Earth mass planet but didn't bother to do the same calculations for the GHG effect of Venus, only for our 1 Earth mass planet Earth. I say used the same reasoning precident that exist in the Gliese 581 c article simply stating the GHG of Venus in the same article paragraph. 24.78.166.69 (talk) 06:19, 30 September 2010 (UTC)

Venus Earth GJ 581 g
Equilibrium Temperature 255 K (-18°C) 228 K (-45 °C)
Surface Temperature 288 K (15°C) 209 K (-64 °C)
add Earth's GHG effect 242 – 261 K (-31°C to -12°C)
add Venus' GHG effect

-still working on it. I'll get this yet. 24.78.166.69 (talk) 06:43, 30 September 2010 (UTC)

The temperature of the planet is strongly dependant on the albedo, and it doesn't seem like the chart above includes this information. Constant insolation of ~700 W/m2 is greater than the average insolation of any place on the earth, including the poles during the 6 months of summer, so with a suitably low albedo (~.15 would lead to average surface insolation of something like 300 W/m2, but this is very dark and would have to be due to something like biological processes) it could well be nearly as warm as Earth (once albedo and rotation effects are taken into account, average insolation of the earth's surface is on the order of 450-500 W/m2, while Mars is somewhere around 200 W/m2). It's also entirely plausible that there are large areas of the planet on which liquid water could exist. It seemed like the paper referencing earthlike temperatures assumes that, as the planet is tidally locked, it may be possible for there to be warmer areas on the subsolar portion of the planet - It may be 200k on the antisunward side, but 300k on the sunward facing portions of the surface. This depends a lot on the existance of an atmosphere and its properties. I'm looking forward to future studies regarding this planet so that we can get some solid information. Isn't the James Webb telescope supposed to be able to directly detect IR emissions of planets like this one? Should make for some good science. Standard original research warnings apply. shaggy (talk) 06:45, 30 September 2010 (UTC)
The chart actually does include albedo, Steven S. Vogt et al used a 0.50 Albedo to come up with their "Surface temperature."
Your not reading the published paper the article is based on yet still comment here is starting to get annoying.
Your comparing direct Irradiance with modified Isolation is wrong, you don't have surface or atmosphere features to make those modifications.

This is a full Irradiance chart for those interested:

Adj Bol. Luminosity Irradiance Planet Percent of Earth
Luminosity (Watts) Periastron Semi-Major Apastron Name Periastron % Semi-Major % Apastron %
0.013 4.99435E+24 19732.211 19732.21 19732.21 Gl 581 e 1444.44% 1444.44% 1444.44%
0.013 4.99435E+24 10564.539 10564.54 10564.54 Gl 581 b 773.35% 773.35% 773.35%
0.013 4.99435E+24 5260.972 3624.28 2647.59 Gl 581 c 385.11% 265.31% 193.81%
1 3.84181E+26 1313.030 1366.08 1422.40 Earth 96.12% 100.00% 104.12%
0.013 4.99435E+24 833.015 833.015 833.015 Gl 581 g 61% 61% 61%
1 3.84181E+26 760.79 588.95 467.18 Mars 55.69% 43.11% 34.20%
0.013 4.99435E+24 954.530 366.92 192.67 Gl 581 d 69.87% 26.86% 14.10%
0.013 4.99435E+24 30.909 30.909 30.909 Gl 581 f 2.26% 1.23% 1.23%

=(3.84181E+26/(4*PI()*(149597876600)^2)) / 1366 = 100%
I'll clean up the sig.difs. later thanks.
Point is you could do another chart with variying Emissivity and Albedo to be most accurate.
I can see where they got their

  • 236 – 258 K (-37°C to -15°C) and
  • 242 – 261 K (-31°C to -12°C) from.

24.78.166.69 (talk) 15:31, 30 September 2010 (UTC)

Comparison to Mars / Venus / Mercury

Mars has 0.107 Earth masses as opposed to 3.1 - 4.3 for Gliese 581 g; a day of about 24 h as opposed to an infinite day for tidally locked Gliese 581 g; a surface atmospheric pressure of 0.636 kPa compared to 101 for Earth and an expected higher value for Gliese 581 g. The tidally locked nature of Gliese 581 g means there will be a wide range of stable temperatures present at different locations on the planet at different distances from the subsolar point, including almost inevitably temperatures conducive to liquid water at ambient pressure (very unlike Mars). How is are the conditions on Mars relevant to those on Gliese 581 g? WolfmanSF (talk) 19:00, 30 September 2010 (UTC)

We don't have tidally locked habitable plants in our solar system, or even close, the comparison is born strictly from the teams own figures. No one has removed the tidally locked parts of the section, you don't have to squawk like they have been, and the comparisons are as fair as any others, including the GHG effect of Venus, which for a 3.1 Earth mass planet they were negligent in covering.
Θ - Read the actual Astrophysics Journal paper before you try to judge the comparisons.
Θ - Read the comparisons at Gliese 581 c before you judge any comparisons.
24.78.166.69 (talk) 19:13, 30 September 2010 (UTC)
If we have no comparable planets then what is the need for such a lengthy comparison? It seemed to me stating facts about Mars for the sake of it rather than elucidating the properties of the planet the article is about, Gliese 581 g. On a related point I have just seen comments added about Venus, despite the sources seeming to not be backing up the claims like [1]. What was this meant to support?
On another note I think both of you have broken the three-revert rule in this dispute, please lets keep this debate both civil and in the talk page until a consensus is agreed on the way forward. ChiZeroOne (talk) 19:55, 30 September 2010 (UTC)
I think you are showing a lack of civility in continuing this line of arguing without looking at the presidents, specifically at Gliese 581 c, where the comparisons are also made. I think you are sorely missing the relevence of the dicussions on the talkpage of Gliese 581 c, and this kind of ignorance is root cause of these arguments. 24.78.166.69 (talk) 20:03, 30 September 2010 (UTC)
Sorry, but I haven't stopped reverting because I'm persuaded that your additions are appropriate. From my perspective the lengthy comparison to Mars still doesn't make sense. No explanation for why it is believed to be relevant is provided in the article. Gliese 581 g gets significantly greater irradiance than Mars. It's atmosphere is surely much thicker than Mars's. The statement that "A low atmosphere is similar to a tidally locked atmosphere in that way" doesn't make sense. If there is a wide temperature variation on Mars, that temperature variation occurs at single locations. On a tidally locked planet, that variation is irrelevant to a given location, which should have a fairly stable temperature. As long as there is one zone on the planet with conditions appropriate for liquid water, it is a good candidate for a habitat for life.
There is no justification at all for the extended quote simply to describe the use of the assumption of a similar greenhouse effect on both Earth and Gliese 581 g. Spinning the quote as "less optimistic" without explanation makes no sense. And any explanation would presume that the editor knows better than the authors, which I think is highly unlikely. WolfmanSF (talk) 20:43, 30 September 2010 (UTC)


This planet is far more favorable then Mars, Venuses climate. I'd make a statement like 581G is the second most favorable planet to life known. —Preceding unsigned comment added by Matthurricane (talk • contribs) 22:59, 30 September 2010 (UTC)

Content removed below:

For comparison, Martian surface temperatures vary from lows of about -87 °C during the polar winters to highs of up to -5 °C in summers.[1] The wide range in temperatures is due to the thin atmosphere which cannot store much solar heat, the low atmospheric pressure, and the low thermal inertia of Martian soil.[2] A low atmosphere is similar to a tidally locked atmosphere in that way.

The idea that this planet is not at all like Mars is false. To say it is like Earth is even more false. The Earth is not tidally locked and the heat recieved by this planet as stated in the primary source is inargualby closer to Mars than it is to the Earth. Adding the GHG effect of the Earth to the Equlibrium temperature of the Earth yeilds 15°C according to the paper. But in the case of this planet, adding the GHG effect of Earth to Gliese 581 g at an equlibrium temperature of 209 K (-64 °C) that would then yield a temperature of 224 K (-49°C), and so it is ridiculous to suggest that the comparison is not relevant. Depending on the size of the actual atmosphere the planet could be even colder than Mars. Because of this I am persuaded that Mars temperature are very much relevant in the article, just as Venus temperature are relevant in the Gliese 581 c article. Counterpointing it as less optimistic is a whole separate issue. Other editors have voiced there opinions that the astronomer is not a biologist and has said some very nonsensical things in his paper, his enthusiasm is almost obsessively biased. But that doesn't change the temperature figures that they themselves have published. Whether it is more optimistic or less optimistic is nonsense when compared to the actual figures and calculations in the primary source. GabrielVelasquez (talk) 03:47, 1 October 2010 (UTC)

We don't have any information about this planet's atmosphere at this time, and the paper doesn't cover anything except a very pessimistic scenario that still shows liquid water might exist somewhere on the planet. Can you tell me what the greenhouse effect on this planet would be with a .1 bar atmosphere? how about 1 bar? 10? 100? what if it's a CO2 atmosphere? What if it's a Nitrogen-Helium atmosphere? What if it's got a 3 bar Oxygen-Helium-Nitrogen-Argon atmosphere? Have you considered the effect of oceans? Can you model this and say that it wouldn't have liquid water? We can speculate, but it's not going to do much good without solid data from an observation of the planet, or sophisticated modeling of the planet's evolution and atmosphere, and that's something that will have to be done by researchers, not Wikipedia editors. As editors, we can only put information in the article that is properly sourced, and any comparison to Mars done by an editor is original research and should not be included. If Anon wants to write a scientific paper comparing Gliese 581 g to Mars, submit it for peer review, and have it published, that is when that information should be included in the article. shaggy (talk) 07:54, 1 October 2010 (UTC)

Good grief, another one who reads only what they want to read. The sky is blue does not need a reference, neither does any fair relevant comparison to planets that we know right here in our own solar system, otherwise, the whole article would end up nothing more than series of block quote boxes in various colors from the sources and there would be no article. You do know that Mars is a planet in our solar system, right? - the figures published by the primary source author are similar to the same data for Mars, and Mars is right here in our own solar system. Just because they failed to make the comparison doesn't mean we can't, you completely missed the discussion at Gliese 581 c and the precedent to good article writing that is there, for your own stubborn bias. The comparison using the Earth's Green house gas effect is speculation by the discovery team since no one knows the atmosphere of Gliese 581 g, are you aware this is speculation?? We don't need to provide you with a reference that says the sky is above the ground, their calculations of temperature are directly comparable to the temperatures of Mars. That's just good writing. - GabrielVelasquez (talk) 18:11, 1 October 2010 (UTC)

Seriously? We can say "this planet has an equilibrium temperature similar to the surface temperature of Mars" and give those figures, but that is misleading without a discussion of equilibrium temperatures, and a comparison to Mar's equilibrium temperature (which is something like 218k, -55C, with an albedo of .25) You would also need to discuss the albedo, potential atmosphere, effects of tidal locking, tidal heating, and every other detail that makes this planet almost nothing like Mars. It is fair to compare the equilibrium temperature of this planet and the Earth as was done in the paper because it illustrates why this planet is potentially habitable. If I recall correctly, the paper referenced in the article regarding the habitability of planets in red dwarf systems even makes a point to say that the habitable zone may be further away from the star if the planet is tidally locked. It seems you are pushing a direct comparison with Mars because you personally disagree with the finding that this planet might be habitable, but references are given in the paper for sources that the team used when making the conclusion that this world is possibly habitable, and there is no reason to reject their findings at this time simply because you disagree with them. This is not the same team responsible for the issues over planet c, so your bias against them seems unreasonable. Every time there is an important discovery, (Another good example is Eris), the Wikipedia article generally becomes a focus for speculation and it is important to keep a clear head and only include things that are verifiable. shaggy (talk) 22:41, 1 October 2010 (UTC)
Scary. You think 224 K (-49°C) is not comparable to 218 K (-55°C), hmmm.
You make the point for the comparison without realizing it.
If I disagreed with the primary source authors I wouldn't be quoting them.
Face it, the planet is in the habitable zone, but not ready for colonization.
GabrielVelasquez (talk) 07:44, 2 October 2010 (UTC)
Making a sweeping comparison between Mars and a planet still under study is not at all like saying the sky is blue. First of all, assuming that gliese 581 g is tidally locked, that could mean that temperatures vary greatly depending on how far the location is from the terminator. Even if the terminator is too cold, you could travel toward the sunlit side until you found an ideal temperature. However, we don't know what the atmosphere is like exactly, and how this will affect the surface... as the article describes in greater detail. These questions are very important, so it's reasonable to speculate on them, although we must not jump to conclusions until more facts are known. Bigdan201 (talk) 13:07, 2 October 2010 (UTC)
This is good for a laugh, you are aware that the Earth is not TIDALLY LOCKED, right?
and the primary source reference authors, or so-called discovery team were the first to make what you call "SWEEPING COMPARISONS" with Earth.
Ok so Mars is not like Earth, Gliese 581 g is not like Earth, therefore Gliese 581 g is not like Mars, is that your reasoning??
are you aware that cancels out all comparisons??? GabrielVelasquez (talk) 19:48, 2 October 2010 (UTC)
Of course the earth is not tidally locked, and neither is mars. But all comparisons are not canceled out - the fact is, gliese 581g is the first terrestrial exoplanet that is likely to have liquid water on its surface. Not only that, but its mass and predicted gravity are only somewhat greater than earth. On the other hand, Mars does not have liquid water on its surface, and its mass/gravity is much lower than Earth. The main point of your comparison is temperature, and that is highly uncertain, depending as it does on atmosphere, greenhouse effect, and weather patterns. Not only that, but current predictions indicate that this planet is likely to have a thicker atmosphere, contributing to warming - while Mars has a very thin atmosphere. While this planet may be very different, it is still more sensible to compare it to earth - besides, earthlike characteristics are what we are interested in. It seems that your push for a Mars comparison is merely an agenda. Bigdan201 (talk) 16:47, 3 October 2010 (UTC)
Temperature

Comparisons

Venus Earth Gliese
581 g 		Mars
Global
Equilibrium
Temperature		 307 K (34 °C) 255 K (−18 °C) 209 K (−64 °C) to
228 K (−45 °C)		 206 K (−67 °C)
+ Venus'
GHG effect		 737 K (464 °C)
+ Earth's
GHG effect		 288 K (15 °C) 236 K (−37 °C) to
261 K (−12 °C)
+ Mars'
GHG effect		 210 K (−63 °C)
Tidally
locked		 Almost No Probably No
Refs. [3][4][5]

All this needs is the refences and it can go in the article. GabrielVelasquez (talk) 22:47, 2 October 2010 (UTC)
Updated - GabrielVelasquez (talk) 01:28, 3 October 2010 (UTC)

While Venus does have a slow rotation, it is far from being tidally locked. A tidally locked rotation is prograde - rotation is in the same direction as revolution about the star. Venus' rotation is retrograde. —Preceding unsigned comment added by Mphelbert (talk • contribs) 03:11, 25 October 2010 (UTC)

Parent Star

why is the temperature (252K), obviously the planet's temperature, under the information about the parent star?

also, why is the radius 1.2 - 1.4 solar radii? this would be the planet's radius, and in earth radii.

I have copied the parent star data from Gliese 581 c, because it has the same parent star. (sorry, forgot to post reason for change)Matt The Tuba Guy (talk) 05:51, 30 September 2010 (UTC)

Distance of Gliese 581

This article quotes Gliese 581 as being 20.5 ly from Sol whereas the main article for Gliese 581 lists a distance of 20.3 ly. Which is correct? --Yoda of Borg (talk) 15:24, 30 September 2010 (UTC) Is within the margin of error Quantanew (talk) 16:38, 30 September 2010 (UTC)

I've put this on the image description file but I haven't requested deletion of a media file before and don't want to mess it up! This image (File:Gliese_581g.jpg) appears to be copyvio. The image, [2], is credited on the NASA website to another party (Lynette Cook) which according to [3] means it is copyright and not public domain. As this is an artist's impression I cannot see why a similar one cannot be created that is free-use so this image doesn't appear to satisfy fair-use, unfortunately. ChiZeroOne (talk) 18:02, 30 September 2010 (UTC)

Given that all we know about the planet's appearance is that it is a sphere orbiting a reddish star, I think creating an image shouldn't be too difficult. However, I would argue that an artist's interpretation doesn't add much to an article such as this, when we have so little to go on. Is the image really necessary? Spiel496 (talk) 23:44, 30 September 2010 (UTC)
True, though to be fair this current image does imply chlorophyll-based vegetation around the terminator which is generally considered more amenable to life on these tidally-locked worlds. So it is actually trying to add something to the explanation of the characteristics of this world, but to be honest it has more potential to mislead about the planet's actual habitability than to increase understanding. Perhaps the issue of artists impressions is a point to bring up on the Astronomy or Astronomical Objects WikiProjects? ChiZeroOne (talk) 00:07, 1 October 2010 (UTC)
The artistic image is in the news, so if it survives the licensing, it is a visual reference to the discovery. I only dislike it because the planet ought to be in reddish lighting! Tom Ruen (talk) 23:54, 30 September 2010 (UTC)
Bleargh, the phase of the planet is completely inconsistent with the light source. Furthermore, the star Gliese 581 has roughly the same temperature as a typical incandescent light bulb, so the dark red colour is inaccurate. Icalanise (talk) 00:03, 1 October 2010 (UTC)
Science and art, tricky bedfellows! Probably it was a quick cut&paste mixture because media people want something to look at! I see Gliese 581 d has a wiki-artist. File:Gliese_581_d-v1.jpg. Tom Ruen (talk) 00:48, 1 October 2010 (UTC)
The image is VERY misleadings, as no water or mountains have been discovered, thus we should replace it with a banal almost single color planet, until further information of it's atmosphere is given. Sopher99 (talk) 02:12, 1 October 2010 (UTC)
Not to mention that the dark side of the planet looks much like the light side, which would certainly not be the case if it was tidally locked. Mrienstra (talk) 03:15, 1 October 2010 (UTC)

Here is an image address of one that i think would be better. [4] (from article [5]) Sopher99 (talk) 02:14, 1 October 2010 (UTC)

Another wrongly colored star, and wrongly-phased image. I wonder who is the artist there? Another copy of the image at [6]. Tom Ruen (talk) 02:30, 1 October 2010 (UTC)
The star is a red dwarf, so it is not wrongly colored in the image showed. Sopher99 (talk) 02:37, 1 October 2010 (UTC)
There seems to be differing opinions, but (in both images) either the star is wrongly tinted (too red), or the reflected light of the planet is wrong (not red).
This one is fun, comparing size of planet and earth. [7]. Tom Ruen (talk) 02:39, 1 October 2010 (UTC)
Unfortunately I fear that picture perhaps has the temperature wrong. It is not a good image unfortunately. Sopher99 (talk) 02:43, 1 October 2010 (UTC)
It looks like the second image you found is 'borrowed' from an old rendering for planet c: [8] "Artist's impression of the planetary system in Gliese 581 (Credit: European Southern Observatory)" Tom Ruen Also at [9] from 2007.
At ESO website: [10]: "Artist's impression of the planetary system around the red dwarf Gliese 581. Using the instrument HARPS on the ESO 3.6-m telescope, astronomers have uncovered 3 planets, all of relative low-mass: 5, 8 and 15 Earth masses. The five Earth-mass planet (seen in foreground - Gliese 581 c) makes a full orbit around the star in 13 days, the other two in 5 (the blue, Neptunian-like planet - Gliese 581 b) and 84 days (the most remote one, Gliese 581 d).".
Tom Ruen (talk) 03:06, 1 October 2010 (UTC)
Maybe Don Dixon would like to expand his art? Here's an older artistic images of c:[11], wow, a movie too, [12]. But whatever is picked, someone has to track down the source artists and get licensing permission. Tom Ruen (talk) 02:44, 1 October 2010 (UTC)

A symbolic rendering?

One idea, perhaps the Template:Gliese 581, with image Image:Gliese581.png, which has more "symbolic" colored images, when its updated, each individual article table can have a larger image of the same symbolic world, so used as more a navigation symbol than rendering? 75.146.178.58 (talk) 03:23, 1 October 2010 (UTC)

A tidal locked planet with a day/night cycle

The wiki entry sites a source in claiming that Gliese 581g has day-night cycle the same length as its orbital period, due to it being tidally locked to its star. However, if it's tidally locked to its star, it shouldn't have a day-night cycle at all. I'm talking about the sciencemag.org article. —Preceding unsigned comment added by 207.38.213.229 (talk) 02:21, 30 September 2010 (UTC)

Yes, you are correct this is weird. The moon has a day night cycle because it is tidally locked to the Earth and changes it's facing to the Sun during its orbit around the Earth. If this planet is tidally locked to its star there is no day/night cycle with respect to the star but it does change its facing as it orbits the star with respect to anything else. It is how some people define tidally locked, the orbit period being the same as the revolution period, that causes the confusion. 24.78.166.69 (talk) 02:32, 30 September 2010 (UTC)
If the eccentricity is non-zero, there will be a "day-night" cycle on part of the planet as the day-night terminator will shift due to orbital libration. It looks like the data shows a circular orbit, but this is probably an artifact due to the limited number of observations. Of course, this is original research (even if it is a known behavior of tidally locked objects in eccentric orbits, like the Earth's moon) so it shouldn't go anywhere near the article until properly sourced. I just think it's neat. shaggy (talk) 05:26, 30 September 2010 (UTC)
  • "Gliese 581g is likely to have evolved to a spin-synchronous configuration, leading to one hemisphere of the planet lying in perpetual darkness. Joshi et al. (1997)" Pg.31 - Steven S. Vogt et al.
    HELLO, this is from the main reference; Original Research? What article are you reading? 24.78.166.69 (talk) 06:11, 30 September 2010 (UTC)
My OR warning only applies to my speculation that there is a day-night cycle on limited areas of the planet due to orbital libration. Sorry if that wasn't clear. shaggy (talk) 06:47, 30 September 2010 (UTC)
How can Joshi et al. 1997 talk about Gliese 581 g in 1997, while "the discovery of Gliese 581 g was announced in late September 2010" ?122.117.35.27 (talk) 15:46, 1 October 2010 (UTC)
They're not writing about Gliese 581 g in 1997, they're writing about spin-synchronous (tidal lock) orbits, a topic in planetary physics. Gwen Gale (talk) 15:56, 1 October 2010 (UTC)
The article referenced investigates the habitability of planets in red dwarf systems in general, particularly the difficulties faced by tidally locked planets such as Gliese 581 g is theorized to be. The conclusions of that paper are broadly applicable to any planet found in the habitable zone of a red dwarf. shaggy (talk) 15:58, 1 October 2010 (UTC)


We say Gliese 581 g is expected to be tidally locked to its star, just as our moon is to the Earth - should we point out why (when Earth, for example, isn't)? I'm assuming its because since this is a red dwarf the goldilocks zone is much nearer the star, so the 1/r^3 stuff makes it more likely to be locked William M. Connolley (talk) 14:17, 30 September 2010 (UTC)


Yes, I had an alikened thought. Meanhile, is the orbit believed to intersect the elleptical orbit of d, as the SVG shows? Gwen Gale (talk) 14:32, 30 September 2010 (UTC)

I think the SVG is out of date, as the planets are all said to have circular orbits in the paper. I'll have to look into this.shaggy (talk) 14:56, 30 September 2010 (UTC)

Thanks. It threw me for a loop. (pun alert) Gwen Gale (talk) 15:17, 30 September 2010 (UTC)

Tidal locking would mean the planet would have no axial tilt and therefore no seasonality in any normal sense of the word. Huh? The moon is tidally locked and has an axial tilt of about 6 1/2°. Am I missing something? --ἀνυπόδητος (talk) 13:43, 1 October 2010 (UTC)

different system, different orbital properties. The moon's orbit is complicated by its position as a satellite. Check this out: Orbit of the Moon. shaggy (talk) 14:33, 1 October 2010 (UTC)
Ah, thanks --ἀνυπόδητος (talk) 15:58, 1 October 2010 (UTC)

Mention of "Systematic errors" in calculations is notable

Finally, it is important to keep in mind that, though all 6 planets presented here are well-supported by the calculated reduced chi-squared statistics and also by several different variants of FAP statistics, and the entire 6-planet system is consistent with the combined data set from both teams, caution is warranted as most of the signals are small. And there may yet be unknown systematic errors in either or both data sets. For example, Pont et al. (2010) have recently concluded from a detailed analysis of HARPS CoRoT-7 data that ”On the whole, there is a mounting body of evidence that unexplained variations at the 5-10 ms−1 level may exist in HARPS RVs for targets in the brightness range of CoRoT-7.” GJ 581 is only about a magnitude brighter that CoRoT-7, so it may not be completely out of the question that HARPS data for GJ 581 might also be affected by such unexplained errors. And to be completely fair, the HIRES data set could also have undiscovered systematic errors lurking within. This is very difficult work and there is no shame or dishonor in uncovering residual systematic errors at these levels of precision. Collegial and unabashed – 37 – inter-team comparisons on stars like GJ 581 and GJ 876 will be crucial to quantifying the true precision limits of any team’s data sets. Finally, because of the very small amplitudes involved, allowing significant eccentricities into the Keplerian fitting tree may yield viable alternate solutions. Here, phase gaps in data sets become problematical as fitting routines generally allow eccentricity to utilize these gaps, driving up the eccentricity artificially to enhance the quality of the fit, and hiding much of the velocity swing from eccentricity in the phase gap. Such situations sometimes result in misleading solutions that can overlook or mask additional planets in the system.

- Steven S. Vogt et al. 2010, page 36

24.78.166.69 (talk) 19:04, 30 September 2010 (UTC)

the HIRES data set could also have undiscovered systematic errors lurking within only says that such errors are *possible*, it does not assert their existence, much less prove them William M. Connolley (talk) 08:44, 1 October 2010 (UTC)

Greenhouse effect bit

I think that Two factors that could potentially give Gliese 581 g a greenhouse effect greater than Earth's are the fact that Gliese 581 radiates a greater fraction of its energy output than the Sun at infrared wavelengths, and the possibility that the more massive planet has a correspondingly more massive atmosphere is dodgy. Also, I don't think it is clearly sourced.

The GHE effect works because the atmos is transparent to the insolation and opaque to the emitted IR. The redder the insolation the *less* effective the GH would be on the planet. The thicker atmos is right, though.

I don't think we use it in the article but from the paper it is clear that they don't really have an atmospheric physicist onboard: they can 't decide if increasing the temp by 288/255, or adding 33, is the right way to do the calculation (without thought I don't know either, I hasten to add) William M. Connolley (talk) 08:53, 1 October 2010 (UTC)

Well, peak emission of the star is in the near IR, at 830 nanometers, while re-emitted IR from a body between 250-300k is on the micrometer scale. I'm not sure that the effect would be that different. Until we get a better paper about the possible atmosphere and temperature of Gliese 581 g, we can leave it for now. I'm thinking it won't take too terribly long for someone to run a few models and publish a paper. shaggy (talk) 11:51, 1 October 2010 (UTC)
circulation must be extremely important. i was thinking it would be Venus-like, but then i realized that a large part of Venus' heat originates from loss of water and oxygen due to UV photo-separation in the upper atmosphere. that would not likely occur, here. if the atmosphere were opaque to 830 nm, wouldn't that yield a hotter upper atmosphere, and much cooler, below? -- 99.233.186.4 (talk) 12:56, 1 October 2010 (UTC)
IIRC the models predict that the planetary albedo decreases for planets around red dwarfs because the Rayleigh scattering is less effective and more of the energy is radiated at the same wavelengths as the absorption features for gases like water and carbon dioxide. Without taking into account other effects, this results in an increased effective temperature for the planet. This isn't usually what is meant by the "greenhouse effect" though. Icalanise (talk) 16:19, 1 October 2010 (UTC)

I've just taken out the frequency bit. It doesn't seem to be true (if anything it is the wrong way, but from the above maybe only marginally so) and I don't see it in the ref anyway William M. Connolley (talk) 21:20, 1 October 2010 (UTC)

Edit request from Merkert17, 1 October 2010

{{edit semi-protected}}


The caption under the picture says this is a planet in our solar system. This is inaccurate - it's a planet in another star system, although it is in our galaxy (the Milky Way, of course)


Merkert17 (talk) 19:00, 1 October 2010 (UTC)

Ok, buddy look at the edits, Gliese 581 f is nothing like Venus, the images was replaced to get rid of this deception, and in the mean time a tidally locked planet image was placed there, it doesn't say that is THE planet, it says it is an image of a planet in our solar system that is also tidally locked. GabrielVelasquez (talk) 19:16, 1 October 2010 (UTC)

I can't find any picture that matches this description, so I've declined your request. Feel free to make it again if you're more specific. Nyttend (talk) 21:46, 1 October 2010 (UTC)

Pic

is a nice pic from Habitability of red dwarf systems. Perhaps we could get one with 581 on it William M. Connolley (talk) 20:03, 1 October 2010 (UTC)


The necessity of locking the article.

The articles contents have not been universally publisised under the title given to it by wikipedia, so, as vandals typically take the pth of least resistance to trashing an article, is this likely to be necessarily an article they can refer to once the media hype goes down, as it almost inevitably will, on this subject? I don't think the page should have an auto-confirmation lock for more than a couple of days.--Cymbelmineer (talk) 21:10, 1 October 2010 (UTC)

The article was protected by request because of unacceptable edit warring, not randoms vandalising. ChiZeroOne (talk) 21:33, 1 October 2010 (UTC)

Discovery Date?

In the article's body, Gliese 581G is reported to have been discovered in September 2010. However, in the "Discovery information" in the little box on the right hand side, the date is given as 21 April 2009. I can't seem to find anything with an actual discovery date to be able to rectify the problem... —Preceding unsigned comment added by 71.182.244.39 (talk) 05:42, 30 September 2010 (UTC)

"We have had GJ 581 under survey at Keck Observatory for over a decade now. In this paper, we bring 11 years of HIRES precision RV data to bear on this nearby exoplanet system. Our new data set of 122 velocities, when combined with the previously published 119 HARPS velocities, effectively doubles the amount of RVs available for this star, and almost triples the time base of those velocities from 4.3 years to 11 years." - pg.6, Steven S. Vogt et al.
Thats because what they did was merge observation measurements from over eleven years into one set and redid the cancellation algorithm to have only 20 extra things that might be interferometry errors for the best cancellation and say it must be six planets. The publish date of the astronomy article will have to do. 24.78.166.69 (talk) 06:24, 30 September 2010 (UTC)
Well done! Now its actual date of discovery is perfectly wrong in the box on the right as well as in the article itself. Otherweise I wonder, why the given references all date "back" to September 2010. If it was discovered all the way back in April 2009: Prove it! I need a reference. And what on Earth is this going to mean:
In an interview, co-discover Steven Vogt claimed "that chances for life on this planet are 100 percent."
Ah, the chances are 100% -- this could only mean utter certainty; besides being also utter nonsense: Go spread the word! There's alien life on Gliese 581g! If anyone doesn't buy it, don't bother, there still is Wikipedia! And this is what Wikipedia says. Hilarious. Zero Thrust (talk) 06:29, 30 September 2010 (UTC)
I can't disagree with you, the hype is going to be ridiculous, it can't remain in the article or again Wikipedia will be negligently responsible for false hype like Gliese 581 c. 24.78.166.69 (talk) 15:35, 30 September 2010 (UTC)
The chances of life in a habitable zone are high. We know that to be true on Earth. Life finds a way in extreme environments. Wherever conditions are right for liquid water, we find life. It does not mean that there is a 100% chance of life being found. Viriditas (talk) 21:05, 30 September 2010 (UTC)
I agree that much of this astronomer's claims are nonsense, as he ignores the fact that very little of the planet is of habitable temperature, and we should give opinions from biologists. Sopher99 (talk) 02:08, 1 October 2010 (UTC)
Astrobiologists actually, and I agree some of what he says is nonsensical.GabrielVelasquez (talk) 05:29, 1 October 2010 (UTC)
You can agree all you want, but what he says is accurate. In other words, it is likely that the chances for life in a habitable zone where liquid water can exist are very good. Please stop reading things into it that aren't there. There's nothing "nonsensical" about it. Viriditas (talk) 07:51, 2 October 2010 (UTC)

Experts needed

I think we need experts for the several disputes discussed above, but also for the article style regarding this subject. Styath (talk) 19:47, 30 September 2010 (UTC)

I agree there seems to be too much arguing that stems from ignorace of the precidents in the article and talkpage of Gliese 581 c. I think they are showing a lack of civility in continuing this line of arguing without looking at the presidents, specifically at Gliese 581 c, where the comparisons are also made and already debated and are included. I think you are sorely missing the relevence of the dicussions on the talkpage of Gliese 581 c, and this kind of ignorance is root cause of these arguments. 24.78.166.69 (talk) 20:03, 30 September 2010 (UTC)
No, it looks like you are edit warring, and cherry picking quotes out of primary sources to say something they don't say. You need to stop. Viriditas (talk) 20:36, 30 September 2010 (UTC)

"Cherry picking quotes" - that's a little harsh from what I saw the quotes from the primary source were relevant to the section it was applied to. Temperature and Habitability are not related?? - I seriously believe you are editing on the wrong topic. The idea that this planet is not at all like Mars is false. To say it is like Earth is even more false. The Earth is not tidally locked and the heat recieved by this planet as stated in the primary source is inargualby closer to Mars than it is to the Earth. Adding the GHG effect of the Earth to the Equlibrium temperature of the Earth yeilds 15°C according to the paper. But in the case of this planet, adding the GHG effect of Earth to Gliese 581 g at an equlibrium temperature of 209 K (-64 °C) that would then yield a temperature of 224 K (-49°C), and so it is ridiculous to suggest that the comparison is not relevant. Depending on the size of the actual atmosphere the planet could be even colder than Mars. Because of this I am persuaded that Mars temperature are very much relevant in the article, just as Venus temperature are relevant in the Gliese 581 c article. Counterpointing it as less optimistic is a whole separate issue. Other editors have voiced there opinions that the astronomer is not a biologist and has said some very nonsensical things in his paper, his enthusiasm is almost obsessively biased. But that doesn't change the temperature figures that they themselves have published. Whether it is more optimistic or less optimistic is nonsense when compared to the actual figures and calculations in the primary source. GabrielVelasquez (talk) 03:47, 1 October 2010 (UTC)

I'm not sure what you are on about. What nonsensical things were said in the paper? Viriditas (talk) 09:55, 1 October 2010 (UTC)
Now who is cherry picking, Ignoring your own discussion above: "Chances of life are 100%" - GabrielVelasquez (talk) 18:28, 1 October 2010 (UTC)
Please try to follow this discussion more closely. You said that the author "said some very nonsensical things in his paper." Could you point me to the page number please? Viriditas (talk) 19:26, 1 October 2010 (UTC)
You try to follow the discussion more closely, you're ignoring the similar comments in that section just to badger me.
Is hypocrisy in your vocabulary?? - GabrielVelasquez (talk) 20:06, 1 October 2010 (UTC)
I'll take that as a retraction of your previous statement. Thank you for conceding. Viriditas (talk) 20:16, 1 October 2010 (UTC)
Petty, very petty. - GabrielVelasquez (talk) 07:32, 2 October 2010 (UTC)
You want petty? As User:ChiZeroOne originally observed, you started editing only after article protection was implemented, preventing User:24.78.166.69 from continuing to edit war. Strangely enough, your first edit after protection was to "warn" User talk:WolfmanSF about edit warring with 24.78.166.69. So, let me ask the question that ChiZeroOne asked of you earlier and that I didn't see you answer. Are you 24.78.166.69? Think carefully before you answer yes or no. Viriditas (talk) 07:48, 2 October 2010 (UTC)

i have a question

if this planet does not rotate does that have an effect on the gravity of the planet? i was just thinking that if the planet not rotating causes weaker gravity the estimated gravity might be wrong... sorry if its a dumb question —Preceding unsigned comment added by 76.120.39.39 (talk) 22:23, 1 October 2010 (UTC)

A planet in tidal lock rotates (as does the moon). If the planet were not rotating (highly, highly unlikely), gravity might be ever so slightly stronger, not weaker. Gwen Gale (talk) 22:38, 1 October 2010 (UTC)

oh ok thanks for the info —Preceding unsigned comment added by 76.120.39.39 (talk) 22:49, 1 October 2010 (UTC)


Speaking of which, does anyone have more info/sources on the surface gravity? the citation, while being good, does not make this clear to me. Gravity is very important for potential colonization. Bigdan201 (talk) 15:37, 2 October 2010 (UTC)

The reason it is not clear is because it is not currently possible to know. The radial velocity method of detection can only give the object's mass (even then as you can see only a range of possible values), not it's radius or mean density. Worlds with a mass of 3-4 times that of earth are expected to be of predominately rocky composition hence a range of mean densities similar to rock are assumed and from both that and the mass the likely value for the radius is calculated. The surface gravity is obviously very dependant upon where the surface is. This is why they state a range of possible values, but then even these are simply educated guesses. There will be no more authoritative values until the planets other characteristics are better defined, which in many cases may require new technologies/methods. ChiZeroOne (talk) 16:08, 2 October 2010 (UTC)
Ah ok, thanks. I will say that the current educated guess of 1.1 - 1.7g is promising. I'm sure that astronomers will conduct a thorough investigation with the tools available, given this planets unique nature. Then we may find out about gravity as well as other important conditions that haven't been confirmed yet. Looking forward to it! Bigdan201 (talk) 16:22, 2 October 2010 (UTC)

grammar correction

Since this is locked: The line "Such a wide range in temperatures is due to the rarefied atmosphere," needs to be corrected to this for plural-singular agreement "Such a wide range in temperature is due to the rarefied atmosphere," Not sure the first comma after atmosphere is needed either. Jascal (talk) 06:49, 2 October 2010 (UTC)

Corrected. None of the commas were actually needed. I just love, the tendency people have, to insert extra commas to better replicate the pauses, and cadence, of normal speech. shaggy (talk) 07:55, 2 October 2010 (UTC)

Radius and surface gravity in the infobox

Do the radius and surface gravity values really belong in the infobox? Unlike the other quantities there, these are unconstrained by actual observations. Probably it is worth mentioning the estimates in the article, but I think that putting them in the infobox gives them far too much validity. Icalanise (talk) 20:16, 2 October 2010 (UTC)

Agreed; removed. — Aldaron • T/C 20:27, 2 October 2010 (UTC)

Orbit and template rendering

I looked at the SVG source, easy and well-documented, so I added a circular orbit for g, crossing elliptical orbit of larger planet d. I wouldn't expect cross-orbits this to make for long term stability! Tom Ruen (talk) 05:19, 30 September 2010 (UTC)

Interesting, in the paper they didn't show 'd' was elliptical (in Fig. 6 in the paper).Tallerjp (talk) 13:57, 30 September 2010 (UTC)

  • So, has it been settled whether the orbits cross each other or not? And whether d has an elliptical orbit or not? I'm a bit confused by the changing diagrams. Bigdan201 (talk) 08:44, 1 October 2010 (UTC)
The elliptic orbits might have been an artifact of the other undetected planets in the system. This is one of the limitations of the radial velocity method. The 6-planet solution in the paper supposes that the orbits are all circular, so for now this diagram is correct. shaggy (talk) 11:26, 1 October 2010 (UTC)

Only four stars are shown in the template graphic but there are six in the list that follows. Can someone update the graphic/template please? Philg88 (talk) 12:12, 30 September 2010 (UTC)

The two newest planets were announced very recently, the article is still being edited to update it with this information. I am sure it will get done. shaggy (talk) 12:32, 30 September 2010 (UTC)
I've updated the diagram to use the circular-orbits 6-planet solution in Vogt et al. (2010), available here. An updated version of this diagram incorporating the orbit of the outer planet f is on my to-do list. Icalanise (talk) 23:52, 30 September 2010 (UTC)
I decided to have some fun, updated the template image and mapping. Feel free to change. I just tried to give very approximate positioned new images, with larger worlds for higher masses, and vague symbolically rescaled spacings. The new image is Image:Gliese581_2010.png, and the same old template was used, with new mappings. Tom Ruen (talk) 04:08, 1 October 2010 (UTC)
It looks good. shaggy (talk) 07:58, 1 October 2010 (UTC)
I doubt it is good idea to have photoshopped planet photos. Someone WILL thought that is how these planets really look. Just white orbs (size proportional to mass, maybe log) on black background. We do not have more data than that and any informative picture should reflect that.89.72.209.44 (talk) 17:21, 7 October 2010 (UTC)
Yeah, I agree with you. It looks very good but why did you put coloured/edited versions of Neptune, Earth, Venus,etc.?

We don't even have any explanation to why they should be coloured this way. Some people will probably believe that they do look like those.So we may need to make some changes to those pictures. For now it would be nice if you used models from out own Solar system to compare their sizes to our planets.Blueknightex (talk) 10:43, 11 October 2010 (UTC)

"Chances of life are 100%"

Vogt's claim that chances of life on the planet are 100% is nonscientific and somewhat ridiculous in an article like this that is otherwise so scientific. I'd suggest we should either 1) remove this claim, 2) tone it down (saying simply that he is optimistic about the prospects of life should be enough) and/or 3) supplement it with opinions of other researchers. Offliner (talk) 15:05, 30 September 2010 (UTC)

I think it's helpful to let readers know about one of the co-discoverer's eager outlook on this, which he himself says is not scientific: Sourced opinion is ok and this opinion has indeed gotten coverage. Sourced reaction to the opinion is also ok. Gwen Gale (talk) 15:16, 30 September 2010 (UTC)
I think many editors are misinterpreting what is being said here. Vogt is saying the chances of life in a habitable environment are 100%, not that there is a 100% chance of life being found. Even I was confused when I first heard it. Viriditas (talk) 21:04, 30 September 2010 (UTC)
He said "“the chances of life on this planet are almost 100 percent.” I don't think he or any of us know what we're talking about and moreover, I think he hinted at that too, in his own way. Gwen Gale (talk) 21:40, 30 September 2010 (UTC)
The quote was taken from the full NSF interview (it is in the external links section). Out of context of the interview as a whole, it doesn't make much sense, however, when you put the quote into context of what Vogt is talking about, the "chances" he is referring to are the chances of life finding a way to survive. Remember, he prefaced this statement with, "given the ubiquity and propensity of life to flourish wherever it can". In other words, given what we know about extreme environments (see extremophile), what Vogt was saying is that the chance of life in such an environment is very high. This is the foundation of the assumptions behind astrobiology. Viriditas (talk) 21:48, 30 September 2010 (UTC)
He said, after being nudged, "the chances of life on this planet are almost 100 percent."[13] By "this planet" he straightforwardly meant Gliese 581 g. Life has a somewhat wide meaning in biology, if that's what you mean. Either way, it's utter, eager speculation. Gwen Gale (talk) 21:56, 30 September 2010 (UTC)
As I explained previously, the NYT article you quote was taken from the full NSF video interview linked at the bottom of this article. The NYT took that quote out of the context of the original interview. Viriditas (talk) 22:00, 30 September 2010 (UTC)
I think it highly unlikely that his English is that weak. Gwen Gale (talk) 22:05, 30 September 2010 (UTC)
His English is very good. The problem isn't with his language, but with the media culture of sound bites. Viriditas (talk) 23:53, 30 September 2010 (UTC)
I am in favor of doing option #3, as he is not even a biologist, and he is ignoring the temperature factor Sopher99 (talk) 02:06, 1 October 2010 (UTC)
As you can see and hear from this brief excerpt, Vogt is clearly not saying life exists on the planet. This was a soundbite dug up out of context in the full interview by various news organizations. Vogt is only talking about the chance of life existing in a habitable zone. In other words, Gilese 581 g may be hospitable to life. That's it. There is no reason to take option 3, because that would mean supplementing a misinterpretation, which is beyond silly. There are ways to further explain this in the context of the original interview, but the link I just gave you shows he is not saying there is life on the planet. So, really, nothing to "supplement". Viriditas (talk) 02:34, 1 October 2010 (UTC)
Ok then, change the article to fit your reasoning then, I agree with your statement. Sopher99 (talk) 02:35, 1 October 2010 (UTC)
Well, I also agree it is confusing people, and it had me confused until I watched the video. I know how to make it clear, but it's going to take me at least a day or so to fix it. Viriditas (talk) 02:37, 1 October 2010 (UTC)
Thats ok as long as it is changed to your statement. Sopher99 (talk) 02:38, 1 October 2010 (UTC)
My local TV newscast just today stated that this planet is "habitable for people." This is truly ridiculous also, and I hope you continue to qualify the statements in the article so the are not as ridiculous as that. The layman that reads this article is not going to look at "Habitable" in the same way an astrobiologist is going to, so you also definitely need to qualify habitability in the article with reference to extremophile life. There is an Associated press article that does that very well quoting the primary source author and then talking about bacteria and mold. I will find it and post a quote here. GabrielVelasquez (talk) 05:25, 1 October 2010 (UTC)
That same AP article quotes Vogt as saying "chances for life on this planet are 100 percent." Viriditas, if you've been saying that this "soundbite" would mislead most readers into thinking he meant human life, I don't think that's much of a worry (although some folks always do misunderstand anything they hear in the news about astronomy, given much of what they don't know, they "learned" from Star Trek and so on). Gwen Gale (talk) 08:47, 1 October 2010 (UTC)
Not sure where you got that from. Vogt's commment about the chances for life did confuse people, because many thought he was talking about life existing there now, rather than the chances for life existing within a habitable zone. According to Vogt, it was 100% likely that life could exist within the habitable zone occupied by Gilese 581 g. He didn't make this clear initially, hence the confusion, but when you listen to the entire interview in the full context, this becomes obvious. In other words, based on what we know, it is likely that life could exist in this environment. That's all. Viriditas (talk) 09:54, 1 October 2010 (UTC)

Uses of term Habitability

Oh the arrogance: I'm not talking about your use, I'm talking about reader understanding, That link uses that word, you conveniently ignored that to keep defending your ego. "Habitable environment" is not used anywhere in the article currently and that's point you blindly miss, Habitability is the word, and there is no redirect from that word/link to anything you are talking about. GabrielVelasquez (talk) 18:36, 1 October 2010 (UTC)
Please refrain from any future personal attacks. We are not talking about the word as it is used in law, and the link is your own, which doesn't make much sense. Viriditas (talk) 19:36, 1 October 2010 (UTC)
Yes. Truth be told, since nobody knows anything about the atmosphere or even the surface of that planet, from an editorial outlook I would say any sourced talk about "habitability" or "life" of any kind is utterly rash, to put it mildly and moreover, ripe for wild misunderstandings. It's getting coverage so it should be carried in the text (and what I see there now looks ok so far to me), but I do think this thread is worthwhile. Gwen Gale (talk) 09:19, 1 October 2010 (UTC)
Vindicated, thank you. GabrielVelasquez (talk) 07:21, 2 October 2010 (UTC)
There appears to be confusion between planetary habitability and the concept of a habitable zone, which is the reason this finding is notable in the first place. It is the first "Goldilocks" exoplanet, neither too hot nor too cold, and it is the best example in this class, so far. Viriditas (talk) 09:54, 1 October 2010 (UTC)

"Ecosphere" is a more accurate and less confusing term than "Habitable zone" (??)

I'm convinced from the above discussion that the less commonly used but more accurate term Ecosphere is preferable to continuing to use the vague/confusable "habitable" word. Just bypass the disambigous page and link it directly to the habitable zone article, the benefit is that the words in this article are less confusing to the layman and to the sensationalizing media. Any thoughts?? GabrielVelasquez (talk) 17:37, 2 October 2010 (UTC)

  • Oppose. As one of the editors who helped create and develop the dab page in 2004, I'm afraid you are mistaken. Ecosphere is no longer used as the chosen term in the literature, and fell out of favor several decades ago. Feel free to do a search through the relevant papers on the subject, as I have. There's a good reason our article is located at HZ and not ES. Viriditas (talk) 18:06, 2 October 2010 (UTC)
  • Support. You can pretend the word doesn't exist, but the favorableness factor is still with Wikipedia not adding confusion to an already complex issue and creating hype debate. This isn't a pop journal, it's an Encyclopedia, so we should favor accuracy over stirring up hype debate. GabrielVelasquez (talk) 18:52, 2 October 2010 (UTC)
Note that GabrielVelasquez has been blocked indefinitely due to his disruptive behavior here, and longstanding abusive behavior and sockpuppetry. — Aldaron • T/C 03:47, 3 October 2010 (UTC)
  • Oppose. Policy WP:COMMONNAME is to use the most common term, and ecosphere is used much less frequently for this concept. In fact none of the results on the first page of a Google search for the term "ecosphere" are related to the use of the term for the habitable zone, except for mention on a Wikipedia disambiguation page. Icalanise (talk) 19:05, 2 October 2010 (UTC)
Surely in the history of policy exceptions...You just earlier pointed me a good LINK (Pg.1) on the SCIENTIFIC precedents.
Astrobilogy isn't the most well known hot topic, for example, but you're reasoning would slant to suggest it isn't relevant. GabrielVelasquez (talk) 19:38, 2 October 2010 (UTC)
Nothing I said implies that astrobiology is not a relevant topic. Question is what is the most common name, not how common the most common name actually is. Icalanise (talk) 19:49, 2 October 2010 (UTC)
You misunderstand, I did not say you said, It was a parallel example of reasoning, not a quote.
Here is a quote: Fogg (1992) has concidered both definitions, using the term "biocompatible" to discribe planets that have liquid water, reserving the term "habitable" for those suitable for humans. The term Ecosphere is also used in the same paragraph. - GabrielVelasquez (talk) 21:26, 2 October 2010 (UTC)
Yeppers. I own the book, and the word is no longer used. In fact, it was the following year that James Kasting published his paper on HZ, supplanting the term Ecosphere. Recommend closing this RFC. Viriditas (talk) 22:24, 2 October 2010 (UTC)
  • Oppose. The only thing relevant is which of the two terms is more commonly used in the literature. A quick google scholar search shows that "ecosphere" is hardly used. Also, I second Viriditas recommendation for closing the RFC. GabrielVelasquez appears to have been indefinitely blocked for sock-puppetry. Therefore there is no point in trying to have a further discussion with someone willing to manipulate the system.Chhe (talk) 16:52, 11 October 2010 (UTC)

Confusing illustration

The illustration (File:485014main orbit comparison full 946-710.jpg) for this article is quite confusing. First, it seems to be primarily illustrating Gliese 581 f from the way it is drawn and the fact that only Gliese 581 f's orbit is compared with the orbits in our solar system. Second it make it look like the name Gliese 581 is being applied only to the orbit of Gliese 581 f. Maybe we should remove it until a better illustration, specifically highlighting Gliese 581 g can be found (or made). 208.64.187.110 (talk) 03:46, 1 October 2010 (UTC)

Also, it [planetary diameters?] doesn't seem to be to scale at all. Ideally, that should be mentioned. The2crowrox (talk) 04:43, 1 October 2010 (UTC)

I agree. The planetary diameters in the two systems really need to be to the same scale as each other. As it is, you have the scale of the stars, the scale of the orbits, the scale of the planets of Gliese and the scale of the planets of Sol: a total of four different scales in the same diagram, with nothing to indicate the fact.174.102.23.147 (talk) 22:06, 3 October 2010 (UTC)

Yes, doesn't really belong here. The image is being challenged for deletion (just like the one it replaced), but if it succeeds in licensing, it stil seems to better belong under the star article Gliese 581. Tom Ruen (talk) 04:59, 1 October 2010 (UTC)
One replacement option might be to take the updated SVG orbital diagram (File:GJ581orbits.svg), and make multiple versions, each highlighting a different orbit and planet, and each of those could go into the planet stat boxes. (BUT perhaps that should wait a while in case there're better data available?) Tom Ruen (talk) 05:03, 1 October 2010 (UTC)
I think this illustration is actually misleading. The primary significance of this planet is potential habitability. Gliese is smaller than Sol, so comparing orbits directly makes no sense for that subject. K. the Surveyor (talk) 13:49, 1 October 2010 (UTC)
Actually, no, the significance is that the planet lies within the conservative part of the habitability zone of its star, pointing to the number of potential planets that may also be in this zone around their stars. This has been lost on most of the major media. Viriditas (talk) 00:42, 3 October 2010 (UTC)


This particular illustration is not only misleading it is completely false. Gliese 581 f doesn't get anywhere as much heat as Venus. Gliese 581 c would be just on the inside of the orbit of Venus and Gliese 581 g would be closer to Mars. GabrielVelasquez (talk) 17:36, 1 October 2010 (UTC)

What are you talking about? The present illustration shows the planets of Gliese 581 based on their semi-major axis. For example Gliese 581 f with a semi-major axis of 0.758 AU is slightly larger than the Venusian 0.723 AU which is why it is depicted as being beyond Venus, because it would be. It never claims to describe equivalent temperatures and why on earth should it?
Not only this, but this comment and others made is highly reminiscent of the comments of another editor, 24.78.166.69, further up the page. For clarity, are you the same person? ChiZeroOne (talk) 18:14, 1 October 2010 (UTC)
"Gliese is smaller than Sol, so comparing orbits directly makes no sense for that subject." Hello? - putting Venus and Gliese 581 f adjacent is deceptive, PERIOD.
If you scaled them for star mass they would be no where near each other, Read all the comments not just cherry pick the parts of the ones you disagree with. GabrielVelasquez (talk) 19:47, 1 October 2010 (UTC)
And? In the image Gliese 581 is depicted as smaller than Sol by about the right size. Comparing the orbits on physical scale is entirely appropriate which the image says is what it is doing anyway so there is nothing false about it. Not only that but the difference in radii for this star and Sol corresponds to approximately 0.003 AU therefore even if the image was made comparing semi-major axis directly then it would still be very accurate. Why on earth are you talking about "scaling them for star mass"? That is misleading, certainly in the infobox which people will expect to be a fairly representative representation.
Secondly, given your tone again in common with 24.78.166.69, I ask again are you the same person? ChiZeroOne (talk) 20:19, 1 October 2010 (UTC)
I don't think an image of Pluto fits in there either because it would give a false sense of how the planet would look like. The image is the first thing people will see, thus giving a wrong impression. Styath (talk) 19:17, 1 October 2010 (UTC)
Yes. This comment and the first comment in this section makes enough sense the orbit comparison image could be removed but not to replace with an image of Pluto (or any real planet from our home system). Most of the rest of the comments aside from ChiZeroOne's reflect more confusion than the image. But in any case a generic image of a planet in orbit around a red dwarf could be used until, say, the ESO creates an image which they usually do.Bdell555 (talk) 19:19, 1 October 2010 (UTC)
Well that didn't last long...[14]. Unfortunately I think any image put up will be changed by someone with an axe to grind, the fact is as artists impressions they are all subjective. In fact I doubt it will last long with no image either. ChiZeroOne (talk) 19:46, 1 October 2010 (UTC)
Ok, if you actually read the edit, you would see it said the Pluto image was supposed be a temporary patch, not permanent. Until one appropriate was found.
Also, dismissing the Encyclopedia's requirement of accuracy is somewhat naive, there is no "grudge" in it.GabrielVelasquez (talk) 20:03, 1 October 2010 (UTC)
I like the image being used now (File:GJ581orbits.svg). It isn't incredibly exciting, but at least it isn't confusing. Kaldari (talk) 00:26, 2 October 2010 (UTC)

SETI and Drake equation

I think the drake equation should at least be cite once. Regards. Yug (talk) 15:39, 1 October 2010 (UTC)

Please find secondary sources finding it in relation to this topic. I removed it from this article because I could not. I'm also not comfortable with the SETI content given such prominence in the habitability section. Viriditas (talk) 20:17, 1 October 2010 (UTC)
No source, but Wikipedia rules also say us to use logic. When the article say "If the fraction of stars with potentially habitable planets (η⊕, "eta-Earth") is on the order of a few tens of percent" we are de facto talking about one part of the drake equation. Yug (talk) 10:42, 2 October 2010 (UTC)
Agree. Speaking as one professionally involved with the SETI project, the "Drake Equation" is not any fixed scientific equation or theory, but a convinence to describe possible scenarios: originally by conceived by Frank Drake to demonstrate that it is at least possible life exists around other suns. The terms of the equations are (intentionally) statistically loose, and have, over the years, been constantly experimentally altered to investigate alternative scenarios. There is no single equation that merits mention. The factors of the "equation" should be individually discussed, with supporting reference to their individual importance. Alpha Ralpha Boulevard (talk) 10:47, 2 October 2010 (UTC)
(@Alpha: Agree with who ?)
We are with Gliese 581 g improving the understanding of Drake equation's ne factor, with ne = the average number of planets that can potentially support life per star that has planets
N =
See Drake_equation#Current_estimates_of_the_parameters Yug (talk) 10:51, 2 October 2010 (UTC)
I agreed with the comments made by you and Viriditas, as written. However, there is no "improved understanding", because the Drake Equation does not represent a universal, empirical scientific truth such as Force = Mass x Acceleration or E=MC2. It's a convenience to describe possibilities. Not a testable scientific theory. Each term of the equation is open to debate -- as well as the terms in combination. Drake never intended to create a universal theory. It was a strawman equation for discussion. Hence the need to discuss each assumption (each term of the equation) separately. Alpha Ralpha Boulevard (talk) 11:18, 2 October 2010 (UTC)
Forest for the trees, please. While this is all related to the Drake equation on a historical and conceptual basis, when we speak of eta-Earth in this specific context, we are talking about NASA's roadmap for investigating, finding, and targeting promising planetary systems.[15] We are years and years away from even talking about ETI, with 2020 considered a likely timetable for such a discussion. So, while Drake certainly makes use of this figure in its equation that's not what we are talking about in this article. Talking about ETI in this context, would be like asking an infant to run a marathon. We are in baby step mode until we have more information. Viriditas (talk) 11:16, 2 October 2010 (UTC)
Yes, Viriditas, in essence. We all of us are just guessing now, scientists alike. But to keep the discussion straight, NASA had little to do with the Drake Equation. The equation came from Drake in the 1960s as a tool for demonstation and communication. The NASA SETI project lasted only lasted briefly, in the 1990s. That project did not seek to amplify on existing versions of the equation. Alpha Ralpha Boulevard (talk) 11:46, 2 October 2010 (UTC)
Please read what I wrote again and visit the link I provided. Eta-Earth is used by NASA as part of the roadmap for searching for habitable planets as is its use by Vogt et al. See p.13, "Recommended Missions, Implementation Framework, and R&D Programs".[16] It "helps set mission strategies by determining the number of stellar systems that must be explored to have a reasonable chance of success" of finding potentially habitable planets. We're not talking about the Drake equation here. This is a rebuttal to what Yug is claiming in his reply at 10:42, 2 October 2010. It's the same idea as Drake, but we're using it in a different context. We're not talking about SETI at all here. I realize that a lot of people are confused because of what the MSM is reporting. And, it looks like I was wrong about 2020. Page 20 of the roadmap says we won't even have good data until 2035. Viriditas (talk) 12:36, 2 October 2010 (UTC)

Closed.

Woow, so much argumentations for a so small issue. My former proposal was just "maybe we may add this Drake equation link, curious people interested to know more will then have the possibility to look at it". And that become a deep debate about "does this recent discovery scientifically modify estimations of factors of the Drake equation or not ?" My proposal/this issue don't worth so much human time. Yes: the Drake is just a blur toy, but still interesting to hear about. So let's each of us go to drink a good chocolate or something similar. [If we were in real I would pay your cups and listen at your astronomic stories ;( (<-wishing a real-life wikipedia)]
Thanks for your interesting posts !
Yug (talk) 13:41, 2 October 2010 (UTC)
I've now restored the link to the Drake equation.[17] I didn't see where it fit in an earlier version. Now I do. Viriditas (talk) 13:01, 4 October 2010 (UTC)

Maybe worth checking is below article, saying that 2 years ago there was a signal from this direction (I've put it into article, later deleted due to not confirmed, but let's take a note here so maybe someone can verify it):

http://www.dailymail.co.uk/sciencetech/article-1316538/Gliese-581g-mystery-Scientist-spotted-mysterious-pulse-light-direction-newEarth-planet-year.html

Why did you add this here when I previously explained the problem with this claim on your talk page?[18] Can you explain why you ignored my comment and posted this for a second time? And why is the Daily Mail making this claim in the first place when by all accounts, it is not true? What is going on here? Viriditas (talk) 08:31, 6 October 2010 (UTC)
Have you considered if maybe direction to this two objects is similar? (thanks for help with the facts, I've removed the mentioning about it also in PL Wiki) —Preceding unsigned comment added by 193.111.236.31 (talk) 11:35, 6 October 2010 (UTC)

Name

Does this planet have any candidates for possible names (like Earth, Venus, etc instead of "Starname g")? How long does it usually take for a planet to be named? 68.193.122.145 (talk) 00:29, 3 October 2010 (UTC)

This is the planet's official name. In fact this has become the standard form of exoplanet naming, despite there being no official rule. This is what the IAU (the legal body for defining astronomical names) has to say on the issue, extrasolar_planets. ChiZeroOne (talk) 00:37, 3 October 2010 (UTC)
I thought the astrophysicist who discovered it nicknamed it after his wife Zarmina.--DrWho42 (talk) 04:05, 3 October 2010 (UTC)
Yeah a number of planets have unofficial names like the famous 51 Pegasi b, also known as Bellerophon, but they're never used officially. Same with Eris/Xena. ChiZeroOne (talk) 04:14, 3 October 2010 (UTC)
Ok, then is there/will there be a "nickname" for Gliese g? 68.193.122.145 (talk) 19:54, 3 October 2010 (UTC)
The discussion page should be about material to be put into the article, this is not the place to discuss this or any other general questions on the subject. But to answer, given that any nickname will always be unofficial, you can call it anything you want. As said above Zarmina is used by the discoverer, though I can't see it becoming too popular being a personal name. ChiZeroOne (talk) 06:48, 5 October 2010 (UTC)

I read somewhere that it was called "Michael", then there's that io9 bit about "Gloaming", up this page a bit. I can't remember what the 3rd name I saw was. —Preceding unsigned comment added by 156.34.169.96 (talk) 23:07, 3 October 2010 (UTC)

Statistics

I created a (hopefully) automated and interactive visual timeline of the edits to this article. It can be seen here: https://spreadsheets.google.com/ccc?key=0Aj_U36rhRPNldFUwOW4xaEtqMUxobUR4elVVLTdURmc. If anyone has suggestions on how to improve/generalize it (i.e. so that it works with other articles), let me know :) --Waldir talk 10:51, 3 October 2010 (UTC)

sun or star?

In the first paragraph there is the sentence "dependent on the planet's atmosphere and previous activity of its sun", but is the use of the word "sun" here correct? Or is that solely the name of the star in our solar system and should it be replaced by the word "star"? Styath (talk) 11:09, 3 October 2010 (UTC)

Any star with planets is a sun. Our sun has a name, "Sol", but can also be called the Sun (with a capital S). Without the capital, it's just a generic noun, denoting a star's relationship to its planets. Horologium (talk) 14:08, 3 October 2010 (UTC)
Thanks, that clears things up :) Styath (talk) 21:11, 4 October 2010 (UTC)

Maximum/minimum temperature?

The article only mentions the average temperature on this planet, which, considering that it's tidally locked doesn't mean that much. It is vital to add the extreme limits of temperature, which would be directly in the center of the hemisphere. It's possible to derive at least potential/feasible estimates from the data that's already available.--Hatteras (talk) 16:13, 3 October 2010 (UTC)

Found the following "A first approximation suggests the temperature would be 71 °C on the day side and -34 °C on the night side, though winds could soften the differences by redistributing heat around the planet." [19]. However, it is not clear whether they mean average temperature on a given side or its peak temperature.--Hatteras (talk) 16:20, 3 October 2010 (UTC)
Ignoring the winds is completely wrong, even if the atmos is as thin as 100 mb. There is some stuff at User_talk:William_M._Connolley#Exoplanets_and_the_Intermediate_General_Circulation_Model I'm meaning to paste in some time. There is a copy of the Joshi et al. paper online somewhere... ah yes, [20] William M. Connolley (talk) 16:19, 4 October 2010 (UTC)
Ah thanks for that, just goes to show my preference for not depicting "the" habitable zone on orbit diagrams is justified. Too many potential ways to change the boundaries. Icalanise (talk) 19:12, 4 October 2010 (UTC)


There is no question that the Atmosphere is much more mixed then it would be on mars. That is what the article tries to tell people, but this is no mars with its ability to hold onto a dense respectable Atmosphere. It would be a better idea to compare this to more of a earth, venus like set up but scale it up as it is 3 times the mass. 1# Larger planet=larger core and more geological activity and out gassing into the Atmosphere. 2# Larger planet=more gravity to hold onto a dense Atmosphere. Unless this planet got rammed by a another planet in the last few thousand years and that lefted it without a Atmosphere at all it's very hard for this not to have a dense that can circulate and even out around.

And finally temperature differences within this Atmosphere would make wind, which would make this planet quite able to be near earths temperature. No question a very interesting weather system could be possible.

It's my belief that we just found a world that has a high possibility of being able to be habitable by to creature/alien if life can get going. Not saying there is, but if my thinking above is correct then it is possible.

This is generally what I learned in geology. —Preceding unsigned comment added by Matthurricane (talk • contribs) 02:53, 5 October 2010 (UTC)

Effect of solar wind on the atmosphere

Wouldn't the atmosphere be stripped away by the solar wind, so close to the star? Also, if the planet is tidally locked, would it have a magnetic field to protect its atmosphere at all? Count Iblis (talk) 16:13, 4 October 2010 (UTC)

Why doesn't solar wind scale like insolation? William M. Connolley (talk) 16:19, 4 October 2010 (UTC)

The planet still rotates, it's just very very slow rotation. If it has a molten core, it is likely that there would be a magnetic field. shaggy (talk) 16:27, 4 October 2010 (UTC)

Mercury is semi-tidally locked and has a magnetic field due to its iron core, which is probably the case with the exoplanet in question.--Hatteras (talk) 16:31, 4 October 2010 (UTC)
Yes, I also just read a bit about these issues here:

One concern was that because M dwarfs frequently produce flares, the resulting torrents of charged particles could strip the atmosphere off any nearby planet. If the planet had a magnetic field, though, it would deflect the particles from the atmosphere. And even the slow rotation of a tidally locked M-dwarf planet--it spins once for every time it orbits its star--would be enough to generate a magnetic field as long as part of the planet's interior remained molten.

Count Iblis (talk) 16:49, 4 October 2010 (UTC)

One potential issue is that it may be harder to generate magnetic dynamos on super-Earths anyway, thanks to the increased core pressure which may keep the iron solid. E.g. [21] (I'm pretty sure I saw an actual paper about this, but right now all I can find is the meeting abstract). Icalanise (talk) 19:08, 4 October 2010 (UTC)

A larger world would generate more heat and have a larger core in which would take longer to cool then mars or even the earths. Jupiter and Saturn have magnetic spheres and they're 50-60 times larger then this world. """ —Preceding unsigned comment added by Matthurricane (talk • contribs) 02:59, 5 October 2010 (UTC)

Mechanism of magnetic field generation in Jupiter and Saturn probably arises from the liquid metallic hydrogen layers. With Uranus and Neptune things are less well known, but the field is probably not generated in the core but in the supercritical fluid layers within the planet. Neither of these mechanisms applies to super-Earths. Icalanise (talk) 08:45, 5 October 2010 (UTC)

I would like to add the below as a footnote or as a random fact.

The close proximity is in comparison to other objects in deep space. In order to travel the distance of approximately 20 light-years between our own planetary system and the planetary system of Gliese 581, it would take approximately 775,021.21 years to reach. The length of time stated was calculated using the approximate stated speed of the Space Shuttle, 27,870 km/h, and the distance given for one light-year, 9,460,730,472,580.8 km.

Do not add Below content unless you feel it is needed.

Distance to Gliese 581 = 20 light-years

Speed of Space Shuttle = 27,870 km/h Space_Shuttle

Light-year = 9,460,730,472,580.8 km Light-year

Days in a year = 365

Hours in a day = 24

Here are my calculations:

9,460,730,472,580.8 km x 20 light-years = 189,214,609,451,616 km

189,214,609,451,616 km / 27,870 km/h = 6,789,185,843.258557588805166846071 hours

365 days x 24 hours = 8,760 hours in one year

6,789,185,843.258557588805166846071 hours / 8760 hours in one year = 775,021.21498385360602798708288482 years

--Dr.Magellan (talk) 18:45, 5 October 2010 (UTC)

Fun calculations to get some sense of scale of distance. I'd suggest using a space probe, like New Horizons going to Pluto as a more realistic speed. Also the sun's gravity well, has to be escaped, so that'll slow down the overall speed a bit. NH will pass Pluto at 13.78 km/s in 2015, so that's about half your speed. Also look at Interstellar_travel#Prime_targets_for_interstellar_travel, which includes Gl581 as a target, perhaps that can be cross linked? (see also Interstellar probe) Tom Ruen (talk) 21:20, 5 October 2010 (UTC)
Makes as much sense as adding the amount of time it would take to get to Gliese 581 on a horse. The Shuttle is being retired and it was never meant for interstellar travel. I don't think any such calculation should be added, but for the sake of theoretical speculation, any of the following propulsion systems would be far better suited for the task: Bipomal Nuclear Thermal Rocket Propulsion, Variable Specific Impulse Magnetoplasma Rocket Propulsion/Nuclear Electric Propulsion, MagnetoPlasmaDynamic Propulsion and Magnetized target Fusion. These are systems that will be coming online within the next thirty years, possibly reducing the amount of travel time to as low as few hundreds of years. None of them are science fiction, instead they're being researched by NASA, as is stated in the 2003 HOPE report. --Hatteras (talk) 21:23, 5 October 2010 (UTC)

A Somewhat Different (Simpler?) Calculation (see details below) Gives A Similar Result (786,108 years to the Planet Gliese 581 g - One-Way! - With No Known *Really OK* Place To Land?).

Calculation Details --

GIVEN:
PLANET-DISTANCE (in light-years)
= 2.03 x 10 light-years (Gliese 581 g)
SPEED-OF-LIGHT (in km/hour)
= 1.0792528488 x 109 km/hour (Speed-Of-Light)
ROCKET-SPEED (in km/hour)
= 2.7870 x 104 km/hour (Space_Shuttle)

FIND:
TRAVEL-TIME (in years)

EQUATION:
Basically,
TIME = DISTANCE / SPEED
Or,
TRAVEL-TIME (in years) = PLANET-DISTANCE (in light-years) X

SPEED-OF-LIGHT (in km/hour) / ROCKET-SPEED (in km/hour)

SOLVING:
TRAVEL-TIME (in years) = (2.03 x 10 light-years) x (1.0792528488 x 109 km/hour) / (2.7870 x 104 km/hour)
TRAVEL-TIME (in years) = 786,108 years

In Any Case - Enjoy! :) Drbogdan (talk) 22:40, 6 October 2010 (UTC)

Sorry to be dismissive but how is any of this encyclopaedic enough to add to the article anyway? ChiZeroOne (talk) 22:53, 6 October 2010 (UTC)
I Think It Relates To The Idea Of Just How Really Inaccessible This HZ Planet Gliese 581 g Might Be In Fact - For Example, Even If The Rocket-Speed Was TEN TIMES As Fast As The Shuttle (2.7870 x 105 km/h), Then The Travel-Time Would Be One-Tenth As Long (78,611 years) - Still A *Really, Really* Long Time I Would Think - A Seemingly Quixote Quest - esp At The Moment? Drbogdan (talk) 23:00, 6 October 2010 (UTC)
No objection to citing something like this and adding it. Viriditas (talk) 02:12, 7 October 2010 (UTC)
But that is the same for any object beyond the solar system, and indeed any habitable exoplanet that will ever be found. Space is big, that and its implications should be made clear in the appropriate articles. It isn't a question of being able to cite calculations, though any exhaustive calculations should be cited to show they're not OR, but the fact that just because something may be interesting trivia doesn't mean it should be included in an encyclopaedia article. The fact is, as has been stated above, it is flawed anyway. ChiZeroOne (talk) 03:27, 7 October 2010 (UTC)
CZO, in general, I agree with you and your argument makes sense, but with the discussion of an Earth-like exoplanet, secondary sources often talk about what it would take to travel there, and I believe the Discover Magazine link I offered Drbogdan is only one of many in this regard. Because this is only the first of many Earth-like exoplanets to be announced (wait until the Kepler data is published) we're going to have to come up with a way to address edits like the kind Drbogdan proposes. Viriditas (talk) 07:54, 7 October 2010 (UTC)

Thanks for the suggestion (and Link) - added a brief sentence (and related citation) to the article - hope it's ok - please improve, relocate, etc if you like of course. Drbogdan (talk) 03:58, 7 October 2010 (UTC)

In my view, any calculation of a travel time to Gliese 581 using a spacecraft that is not designed to get there represents a factoid, an interesting but basically irrelevant statistic that serves only to illustrate that 20 light years is a long way by solar system standards. This fact is already obvious simply from the definition of a light year. We could do such a calculation for any extrasolar planetary system. But should we? I would recommend that such a statistic be relegated to a footnote. WolfmanSF (talk) 10:07, 8 October 2010 (UTC)
No point in starting a spacecraft now. In 100 years, there will be faster space-travel so that the ship will overtake the one started now. But no need to start in 100 years to, because in 200 years... :) -Koppapa (talk) 11:17, 8 October 2010 (UTC)

A (much?) better reference (Slate Magazine by Brian Palmer) for the calculated trip time to Gliese 581 g has been found. Seems the published trip time is "766,000 years" (at the speed of the space shuttle) and agrees very well with my own calculated result ("786,108 years") (as well as "775,021.21 years" by Dr.Magellan) noted earlier in this discussion. Perhaps this newer edit (with a better reference) may be more worthy? OTOH, as suggested, maybe all this should be made into a footnote of some kind? Drbogdan (talk) 15:59, 8 October 2010 (UTC)

A footnote at most. It's a meaningless statistic. The speed of the space shuttle is that of all satellites in low Earth orbit and is not relevant to interstellar travel. Anyone can calculate the travel time to Gliese 581 using any assumed speed; it's a trivial calculation. So no reference is really needed. WolfmanSF (talk) 16:44, 8 October 2010 (UTC)
Ok - as noted in the article/revision history, my new edit "changed est planet travel time quote into footnote referenced in lede" - hope the footnote is presented ok - my first time w/ doing this - some other position, wording, etc would be entirely ok w/ me - in any regards - Enjoy! :) Drbogdan (talk) 17:44, 8 October 2010 (UTC)

Checkered history

Despite the authors' admission that "The GJ 581 system has a somewhat checkered history of habitable planet claims" [3] (with claims of habitability having been made and then fully or partially retracted for Gliese 581 c and d, respectively), Vogt was optimistic

There are several problems with this wording. While this is certainly a clever and creative way of using a primary and secondary source, it is not best practice unless the two statements are themselves supported in the context of a secondary. There's also the issue of staying on topic. The "checkered history" part comes from a discussion of historical claims of habitability, not the potential for life; closely related, but different. There's also the problem with the wording. This should not be portrayed as an "admission' versus an optimistic outlook unless the secondary sources say this. Otherwise, this is a minor misuse of a primary. The use of long parentheticals disrupts the flow of the paragraph and should be avoided or moved to a footnote instead. Lastly, there is no good reason to quote this statement as it is very easy to paraphrase the history in the first place. Before I fix this, I wanted to bring this issue to the attention of the active editors. Viriditas (talk) 09:07, 8 October 2010 (UTC)

I disagree several of your claims. First, in this context, "habitability" and "potential for life" are exactly the same thing. Second, all of this is from the primary source. And I disagree that long parentheticals are never appropriate. I included the quote because it's pithy and memorable. However, you may be right that this history could be better described elsewhere. WolfmanSF (talk) 11:20, 8 October 2010 (UTC)
It is also wrong to suggest the claims for the habitability of planet d have been refuted: in fact on the same day as the discovery paper for planets f and g appeared on the arXiv, [22] which concluded that habitability is still possible (though note they are using the orbit from the 4-planet solution which leads to a higher orbit-averaged insolation thanks to the eccentricity). Icalanise (talk) 21:40, 8 October 2010 (UTC)
I said "partially retracted", which is obviously not the same as "refuted". On p. 29 of their paper, Vogt et al. describe the case for habitability of planet d as being marginal. I was referring to that. The conclusion of Paris et al. is similar. WolfmanSF (talk) 00:47, 9 October 2010 (UTC)
"Retracted" implies someone has issued a retraction of their previous claim. Has this happened? Icalanise (talk) 00:52, 10 October 2010 (UTC)
Quite the opposite.[23] The claim has been bolstered, not retracted. Viriditas (talk) 01:00, 10 October 2010 (UTC)
Discussion has been moved and modified to (hopefully) obviate the objections. WolfmanSF (talk) 18:54, 10 October 2010 (UTC)
Please note, Viriditas, that the article you cited to support your argument isn't terribly accurate - they describe planet d as having better prospects for habitability than planet g, which is not the scientific consensus. WolfmanSF (talk) 23:27, 10 October 2010 (UTC)
I have yet to find a MSM source that is accurate when it comes to science. Can you quote the part you claim is wrong? I could not find it. Also, what does that have to do with what we are discussing? Viriditas (talk) 00:00, 11 October 2010 (UTC)
Here is where they screwed up: "However, it is not yet clear whether the planet's climate can support life. According to initial rough estimates, temperatures on Gliese 581 g, which presumably lacks a significantly warming greenhouse effect, are more freezer-like." Most of the (German) article is intended to highlight work done at the Max Planck Institute for Astronomy in Germany, where some modeling of the potential atmosphere and habitability of planet d was carried out. The discovery of planet g probably was announced after the most of the interviewing was done, so the writers based that comment on their own misunderstanding of the science and/or a desire to downplay the significance of the new competing center of attention. They misstated the relative habitability prospects of the 2 planets, and were mainly interested in the possibility of plante d's habitability, without worrying about its probability. What does that have to do with what we are discussing? They didn't describe the science very accurately, so you would have been better off citing a scientific paper(s) as the basis for your argument. WolfmanSF (talk) 10:37, 11 October 2010 (UTC)

Possible satellites

There is probability that moons may exist around this tidally-locked planet if the orbits of the moons are stable against the strong gravitational pull of the star. But in order for moons to be stable, the moon should orbit close to the planet. I’ll say that there will be only one or even two moons in orbit around the planet. I knew that the solar system’s closest planets Mercury and Venus don’t have moons, but a three-earth mass planet in orbit three times closer to the sun than Mercury or five times closer than Venus may beat out Mercury and Venus in having at least one moon. BlueEarth (talk | contribs) 21:33, 11 October 2010 (UTC)

Swiss team data

See: http://www.sciencenews.org/view/generic/id/64308/title/Existence_of_habitable_exoplanet_questioned

It seems that thay think is isn't even there. A. Z. Colvin • Talk 23:58, 13 October 2010 (UTC)

Says not confirmed or refuted:

“Simulations on the real data have shown that the probability that such a signal is just produced 'by chance' … is several percent,” he says. “Under these conditions we cannot confirm the presence of the announced planet Gliese 581g.” Pepe adds, though, that his team can’t formally refute it either.

weather on alleged planet

http://www.technologyreview.com/blog/arxiv/25930/ —Preceding unsigned comment added by 24.0.65.99 (talk) 13:49, 26 October 2010 (UTC)

io9's name

This may or may not be worthnoting but io9 has decided the appropriate name for the planet is "Gloaming".

Source: What a colony might look like on Gloaming, the newly-discovered "second Earth"--DrWho42 (talk) 19:59, 30 September 2010 (UTC)

What drek that is. Gwen Gale (talk) 20:00, 30 September 2010 (UTC)

Here's an article I just read. [24]. I came over to Wikipedia to see if there was already an article.Malke 2010 (talk) 22:11, 30 September 2010 (UTC)

Forgot to mention it's also on Twitter.Malke 2010 (talk) 22:12, 30 September 2010 (UTC)

I disagree, it should be named: наистина много далече, че хората от Земята планета не би могла да достигне в близко бъдеще instead! --TitanOne (talk) 08:12, 2 November 2010 (UTC)

Planet not found in new HARPS data

According to a note that appeared on the Extrasolar Planets Encyclopaedia page for Gliese 581 [25], this planet is not present in new HARPS data for the system, and the planet is listed there as unconfirmed. Icalanise (talk) 07:38, 11 October 2010 (UTC)

That is correct. What's the issue? Viriditas (talk) 08:21, 11 October 2010 (UTC)
Sometimes with these things I prefer to put some evidence on talk page in case people don't read edit summaries or references in the article, especially when topic has a history of needless controversies. Icalanise (talk) 08:33, 11 October 2010 (UTC)
Also dude chill out, if you don't see the point of a section how about just ignoring it, your edit summary comes across as unnecessarily belligerent. Icalanise (talk) 08:41, 11 October 2010 (UTC)
Try not to interpret the emotions or intent of others, such as in the use of the word "so", as you will often find yourself mistaken. So, the planet is unconfirmed. The last section says this, but is this clear in the lead? Viriditas (talk) 08:52, 11 October 2010 (UTC)

Update: I removed the entirety of your latest edit except for the unconfirmed part. You claim to cite a tertiary source which in turn ambiguously cites a primary. Could we please see a transcript of Pepe's talk to see the material in the context it was delivered? Thanks. Viriditas (talk) 09:47, 11 October 2010 (UTC)

Well I'm not actually at the meeting, and the abstract for the talk just says it is a review of the HARPS results [26]. I am not aware of a policy against using tertiary sources. WP:PSTS states that they can be used, with the exception of Wikipedia itself. So question is whether we want to treat EPE as a reliable source or not. Note that EPE has been cited in the scientific literature on several occasions. Icalanise (talk) 10:14, 11 October 2010 (UTC)
Incidentally, the note in EPE is "The planet Gl581 g not present in new HARPS data Pepe et al. 2010" - could you specifically state what you find ambiguous about this? Icalanise (talk) 10:16, 11 October 2010 (UTC)
Adding unverified BLP content based on something someone overheard at a conference isn't helpful. Viriditas (talk) 11:40, 11 October 2010 (UTC)
You are absolutely right about the BLP issues. I think we should blank this article until we can verify beyond all reasonable doubt that everyone named as an author in the references section is exactly who they claim to be and is in fact an author. Icalanise (talk) 12:38, 11 October 2010 (UTC)
Do we know what Pepe said? Viriditas (talk) 12:54, 11 October 2010 (UTC)
Do we know that the Vogt person who was interviewed was definitely the same person who wrote the discovery paper? Can we actually say we saw them all in the process of writing it? How far does this conspiracy go??? Icalanise (talk) 12:56, 11 October 2010 (UTC)
WP:V isn't a conspiracy. I've restored its unconfirmed status. What did Pepe say at the conference? Viriditas (talk) 13:01, 11 October 2010 (UTC)
Well we have to rely on people who were there at the conference to tell us this, unless we were there. The question is then do we trust the Extrasolar Planets Encyclopaedia to report this accurately? As far as I am aware, EPE is a reliable source. However I suppose we could say "the Extrasolar Planets Encyclopaedia reported that in a talk given at IAU Symposium 2010, F. Pepe said that this planet was not found in new data from HARPS". And then we can similarly amend all the references to every source ("a book that the publishers, who claim to be XYZ Publishing House, claimed was authored by ABC, which some Wikipedia editor claims to have read, claims states FGHJKL") Icalanise (talk) 13:08, 11 October 2010 (UTC)
Also if you are so concerned about violating WP:BLP that you don't trust the EPE, why restore the unconfirmed status? You are effectively saying we can take what the source said but that we are not allowed to attribute it... Icalanise (talk) 13:11, 11 October 2010 (UTC)
It is easy to verify the status of the planet. Where can I verify the EPE info? Do they represent the Paris Observatory? Viriditas (talk) 13:19, 11 October 2010 (UTC)
It is easy to verify who the EPE people are. Icalanise (talk) 13:29, 11 October 2010 (UTC)
Are they reporting in an official capacity for the PO? Viriditas (talk) 13:37, 11 October 2010 (UTC)
I'm not their babysitter, why don't you go and find out. Anyways I've realised I am wasting far too much of my time editing Wikipedia, I'm out of here. Icalanise (talk) 13:40, 11 October 2010 (UTC)
There's another source that says the original paper was rejected due to concerns with noise. Viriditas (talk) 13:48, 11 October 2010 (UTC)
Even though this planet is now unconfirmed, I suggest that it is still certain that this planet and f does exist. I think it needs little more time to study this star to confirm the planets g and f more strongly. How does HARPS found this planet two weeks ago and HARPS didn't find the signal of this planet two weeks later? I know that HARPS is the most powerful planet-hunting technique on Earth. Many groups of astronomers should study the star using the different radial velocity techniques in different parts of the world and hopefully astronomers shall finally confirm the existence of planets g and f in the near future. BlueEarth (talk | contribs) 21:49, 11 October 2010 (UTC)
HARPS team never claimed to have seen the planet. In fact, they added the planet solution and got a negative signal[27], meaning that it is not just that HARPS couldn't see it, their data suggest the planet does not exist at all. But of course, that doesn't make it certain that the planet is not there. But the truth is, it does not look good. Sad that Vogt jumped the gun and announced the planet too early (3-sigma detection seems not good enough for such an important detection). — JyriL talk 11:03, 12 October 2010 (UTC)
Were you at the conference? Steinn says he wasn't, so he is acting as tertiary source. No-one else seems to be making this claim, so I think you are violating WP:BLP by posting that thing about negative signal. Where is Viriditas? He should have called you out on this! Icalanise (talk) 16:30, 13 October 2010 (UTC)
Icalanise, you may not be aware of how things work here. Whenever there are breaking stories, and this is a daily occurrence, we have to wait for more than one source to cover the subject, and that one source has to be based on information that anyone can easily verify. You originally used the EPE as this solitary source, which for all intents and purposes is fine. But, in this case, it was information that could not, at the time, be verified, and was basically hearsay. Now that the MSM has covered the topic, there is no problem. Please understand, this is standard procedure and says nothing about you or the quality of the EPE source. Viriditas (talk) 02:04, 14 October 2010 (UTC)
Can you please link the policy stating it has to be in multiple sources. The one you threw at me, WP:V says at several points that the statements must be referred to "a reliable source", which being phrased in the singular form, strongly implies that a single source is acceptable. Icalanise (talk) 17:24, 15 October 2010 (UTC)
As you already know, the EPE was using Steinn Sigurðsson's blog as their source. The use of such a source during a breaking news event is discouraged. We always wait for MSM sources to pick up the story first, which they did the next day. I don't know where you get the idea that this blog or a web site is the best source for a breaking news story, but many of the policies and guidelines recommend against it, preferring that editors wait for significant coverage first. Viriditas (talk) 20:44, 15 October 2010 (UTC)
Do you have actual evidence that EPE was using Steinn Sigurðsson's blog as the source? As I recall, the note on EPE was up before Steinn Sigurðsson's blog was posted. Icalanise (talk) 22:48, 20 October 2010 (UTC)
That may be true, in which case, I will concede the point, however other than the comment at EPE, I am not aware of any other source contemporaneous with the conference announcement. More to the point, is the EPE considered a reliable source for claims that have not been published? I am fairly certain the answer is no since they are a tertiary source that relies on claims previously published by RS. End of discussion. Viriditas (talk) 23:02, 20 October 2010 (UTC)
You keep shifting your argument. Try and be consistent, even if you find it difficult. You avoid my question about where the policy is that requires multiple sources, you assert without proof that EPE is acting as a tertiary source and is unreliable, and you still haven't pointed out the policy that states tertiary sources should be considered as unreliable. You just keep shifting the argument. Your statement "End of discussion" reads to me like yet more avoidance of the issues. Icalanise (talk) 18:41, 21 October 2010 (UTC)
On the contrary, my "argument" has been remarkably consistent based on our policies, guidelines, and best practices, and the only question and issue that has been avoided have been the questions I've asked you about the source. Reliable tertiary sources are composed of previously published primary and secondary sources. Wikipedia depends primarily on secondary sources for her articles, but may use tertiary sources for a general review of already published, uncontroversial information. In most respects, this is precisely how EPE is used. Most, if not all of the data in EPE can be found in peer reviewed publications. However, in this case, someone updated EPE with recent information that could not be verified (against the best practice of a reliable tertiary source) and you added it to this article. At that time, the information could not be verified and was removed appropriately. To date, you have still been unable to verify where this information came from, and you avoided answering my direct question I asked you above at 13:37, 11 October 2010 (UTC), namely, was EPE reporting in an official capacity for the Paris Observatory? If they were, then the source might be reliable. If they were not, then what I've said above still applies. This is very easy to understand, so your continued problem on this point demonstrates issues that are outside this topic. Condensed version: Tertiary web sources are not used to cite breaking news coverage. Viriditas (talk) 04:11, 22 October 2010 (UTC)
Look I am perfectly prepared to agree with your point about tertiary sources if you can point out where this is stated in the policy. You have consistently failed to do this! All I have found from this discussion is that you don't like them, and I am sorry but you not liking them is not basis for Wikipedia policy! Icalanise (talk) 08:21, 22 October 2010 (UTC)
I don't know what you are talking about, and it sounds like you have misinterpreted what has been said here. I have never said anything about disliking a tertiary source and everything I've said here is supported by the relevant policies and guidelines. I'm sorry you do not understand them or what I've said. If you have a specific question I would be happy to answer it, but right now it sounds like you are obsessing over something you can't communicate. A tertiary source reports what has already been published. It does not report breaking news. Viriditas (talk) 21:33, 22 October 2010 (UTC)
I get it now! You know that announcing the discovery of the new planet too early is not so good, because everyone think that new exoplanet is definitely there just like during the solar eclipse, there is evidence that our moon is definitely in orbit around the Earth. After one group of astronomers have claimed to found this planet, I strongly suggest that another groups of astronomers shall look at their data to ever make it more certain that this planet exists or retracted. Perhaps within a year, different groups of astronomers will agree whether this planet actually exists or not. BlueEarth (talk | contribs) 18:13, 12 October 2010 (UTC)

Recent science press coverage: Recently Discovered Habitable World May Not Exist. — Aldaron • T/C 20:25, 12 October 2010 (UTC)

I read this article, interesting. I know that not even the HARPS over their long observing campaigns is perfect for discovering new planets. I know that Vogt was claimed to have found this planet using HARPS and then two weeks later Pepe didn't find the evidence of this planet using the same method that Vogt used. I think that how different people would think about the existence of this planet by looking at their data. Some people think they have found the RV signal of this planet while the others don't think so. So many astronomers will repeatly study the star Gliese 581 and look at their data as they go along until the signal of this planet was found. BlueEarth (talk | contribs) 21:54, 12 October 2010 (UTC)
Another related link is here TheEpochTimes - Also, if interested, Google Search Link re "Gliese 581 g", Latest News. Drbogdan (talk) 23:17, 12 October 2010 (UTC)
The Astrobiology Magazine article is here. It should be used. Viriditas (talk) 23:30, 12 October 2010 (UTC)
FWIW - Apparently Vogt responded via email to Wired re the latest news: “I am not overly surprised by this as these are very weak signals, and adding 60 points onto 119 does not necessarily translate to big gains in sensitivity,” ... He added that the non-detection doesn’t mean the planet doesn’t exist — it may be that it’s only detectable using both data sets. “I do not wish to comment on Pepe’s result as I haven’t seen his data ... But I have tremendous respect for their work, and look forward to seeing their additional data on this and other systems of mutual interest.” Drbogdan (talk) 00:41, 13 October 2010 (UTC)

Also now removed from EPE (as "Unconfirmed, controversial or retracted planets"). — Aldaron • T/C 03:16, 13 October 2010 (UTC)

I added a subsection Unconfirmed, splitting the Discovery section text, and anchor-linked it to the introduction word unconfirmed, to make it more clear what unconfirmed means. Tom Ruen (talk) 11:15, 13 October 2010 (UTC)
I removed the link as it is unnecessary per lead and linking guidelines. As for the subsection, that's a matter of preference, but short, one paragraph sections are generally discouraged. Viriditas (talk) 11:23, 13 October 2010 (UTC)

I think that astronomers may have overestimated its mass. Even if the planet's signal is not found in HARPS data, then this planet may still exist with the mass maybe between 1–2 MEarth, which is impossible for HARPS to detect even at the distance of 0.14 AU from the red dwarf star. I'll say that the radial velocity technique more powerful than HARPS would detect that signal. BlueEarth (talk | contribs) 22:31, 13 October 2010 (UTC)

Recently added more (hopefully relevant) discussion to the "Nondetection in new HARPS data analysis" section in the main article (based on several recently published references) - please feel free to improve as needed of course. Drbogdan (talk) 14:19, 14 October 2010 (UTC)
Added latest news to Main Article re Gliese 581g being an "apparition" in data interpretation - ref Seth Shostak, Michel Mayor, Huffington Post, 11/01/2010 - Please feel free to improve placement, wording, and all as needed of course. Drbogdan (talk) 01:40, 2 November 2010 (UTC)
It's not clear from the HuffPo (which sometimes has "problematic" science coverage), but Francesco Pepe is part of Mayor's group in Geneva. At the moment, it looks as if these are two independent opinions, when this is probably the same result (possibly, Shostak even references the same statement, although, again, that's not clear from the source). --Stephan Schulz (talk) 07:20, 2 November 2010 (UTC)
Thanks for your comment - I agree - Shostak *may* be referring to the earlier study by Pepe - and not a totally new one after all - I've not been able to find another reference supporting a newer study - so far at least - guess we may have to wait further to see if the presence of GL581g is confirmed or not - please feel free to omit/modify my recent addition to the main article as needed of course. Drbogdan (talk) 13:51, 2 November 2010 (UTC)

I think when this planet was claimed to be found and then retracted to an unconfirmed status would be a planetary equivalent to the blown call by an umpire that cost Armando Galarraga of the Detroit Tigers a perfect game coming with two outs in the ninth inning on June 2, 2010. BlueEarth (talk | contribs) 20:37, 13 November 2010 (UTC)

  1. ^ "NASA, Mars: Facts & Figures". Retrieved 2010-01-28.
  2. ^ "Mars' desert surface..." MGCM Press release. NASA. Retrieved 2007-02-25.
  3. ^ a b Cite error: The named reference Vogt was invoked but never defined (see the help page).
  4. ^ Stephens, Tim (2010-09-29). "Newly discovered planet may be first truly habitable exoplanet". University News & Events. University of California, Santa Cruz.
  5. ^ "NASA, Mars: Facts & Figures". Retrieved 2010-01-28.
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