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Lahaina Noon

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(Redirected from Zero shadow day)
A level photographed during Lāhainā Noon in Hawaiʻi
Students performing an experiment on a zero shadow day

Lāhainā Noon, also known as a zero shadow day, is a semi-annual tropical solar phenomenon when the Sun culminates at the zenith at solar noon, passing directly overhead (above the subsolar point).[1] As a result, the sun's rays will fall exactly vertical relative to an object on the ground and cast no observable shadow.[2] A zero shadow day occurs twice a year for locations in the tropics (between the Tropic of Cancer at approximate latitude 23.4° N and the Tropic of Capricorn at approximately 23.4° S) when the Sun's declination becomes equal to the latitude of the location, so that the date varies by location.[3] The term "Lāhainā Noon" was initiated by the Bishop Museum in Hawaiʻi.[4]

Details

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The subsolar point at Honolulu during Lahaina Noon with the range of possible subsolar points shaded in purple – the angle between the Sun and the local horizontal level is exactly 90° at the subsolar point

The subsolar point travels through the tropics. Hawaiʻi is the only US state in the tropics and thus the only one to experience Lāhainā Noon.[5] In 2022 and 2023, the phenomenon occurred in Honolulu on May 26 and July 16.[4] Hawaii and other locations between the Tropic of Cancer and Tropic of Capricorn receive the sun's direct rays as the apparent path of the sun passes overhead before and after the summer solstice.

Lāhainā Noon can occur anywhere from 12:16 to 12:43 p.m. Hawaii–Aleutian Standard Time. At that moment objects that stand straight up (flagpoles, bollards, telephone poles, etc.) cast no outward shadow. The most southerly points in Hawaii experience Lāhainā Noon on earlier and later dates than the northern parts. For example, in 2001 Hilo on the Island of Hawaiʻi encountered the overhead sun around May 18 and July 24, Kahului, Maui, on May 24 and July 18, Honolulu, Oʻahu, on May 26 and July 15 and Līhuʻe, Kauaʻi, on May 31 and July 11. Between each pair of dates, the sun is slightly to the north at solar noon.[6]

Chosen in a contest sponsored by the Bishop Museum in the 1990s, Lāhainā Noon was the selected appellation because lā hainā (the old name for Lāhainā, Hawaii) means "cruel sun" in the Hawaiian language.[7] The ancient Hawaiian name for the event was kau ka lā i ka lolo which translates as "the sun rests on the brains."[5][8]

Subsolar dates

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Approximate subsolar point dates vs latitude superimposed on a world map, the example in blue denoting Lahaina Noon in Honolulu
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The event is often covered by Hawaiʻi media.[5][9][10][11] Activities are associated with the event.[12]

Sky Gate, a unique sculpture in Honolulu created by artist and landscape architect Isamu Noguchi, features a bendy, bumpy ring that has large changes in height around its circumference. Most of the year, it makes a curvy, twisted shadow on the ground, but during Lāhainā Noon, the height-changing ring casts a perfect circular shadow on the ground.[13] There are often activities held by the City & County of Honolulu around the time of the event on the Frank Fasi Civic Grounds, where the sculpture is located.

The phenomenon occurs in stories, including "Lāhainā Noon" by Eric Paul Shaffer (Leaping Dog, 2005),[14] which won the Ka Palapala Po'okela book award for Excellence in "Aloha from beyond Hawai'i".[15][16]

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See also

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References

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  1. ^ "Clock, sun rarely match at noon". Honolulu Star-Bulletin. December 31, 2008. Archived from the original on July 17, 2023. Retrieved July 16, 2023.
  2. ^ Newsd (2019-04-24). "Zero Shadow Day 2019: Date, time & know why you cannot see your shadow". News and Analysis from India. A Refreshing approach to news. Retrieved 2019-08-22.
  3. ^ "Zero Shadow Day". ASI POEC. 2017-04-07. Retrieved 2019-08-22.
  4. ^ a b "Lāhainā Noon". Bishop Museum. Retrieved August 3, 2022.
  5. ^ a b c Nancy Alima Ali (May 11, 2010). "Noon sun not directly overhead everywhere". Honolulu Star-Bulletin. Retrieved November 12, 2010.
  6. ^ "'Lahaina Noon' coming here soon". Honolulu Star-Bulletin. May 23, 2001. Retrieved November 12, 2010.
  7. ^ Mary Kawena Pukui; Samuel Hoyt Elbert; Esther T. Mookini (2004). "lookup of Lā-hainā ". in Place Names of Hawai'i. Ulukau, the Hawaiian Electronic Library, University of Hawaii Press. Retrieved November 12, 2010.
  8. ^ Mary Kawena Pukui; Samuel Hoyt Elbert (2003). "lookup of Lolo". in Hawaiian Dictionary. Ulukau, the Hawaiian Electronic Library, University of Hawaii Press. Retrieved May 26, 2011.
  9. ^ "Newswatch: Shadows disappear today at Lahaina noon". Honoluu Star-Bulletin. May 27, 2006. Retrieved August 22, 2017.
  10. ^ Kaichi, Carolyn (April 29, 2007). "Earth at prime tilt to view Mercury at apex". Honolulu Advertiser. Retrieved August 22, 2017.
  11. ^ Miura, Kelli (July 11, 2008). "Lahaina Noon flits over Honolulu on Tuesday". Honolulu Advertiser. Retrieved August 22, 2017.
  12. ^ "Liliha Library to host 'Lāhainā Noon,' 'StarLab' astro events". Honolulu Advertiser. July 15, 2008. Retrieved August 22, 2017.
  13. ^ Keany, Michael (June 30, 2008). "Skygate". Honolulu magazine. Retrieved September 9, 2020.
  14. ^ Adams, Wanda A. (June 26, 2005). "'Lāhainā Noon' about a warm, clear feeling". Honolulu Advertiser. Retrieved August 22, 2017.
  15. ^ "Ka Palapala Po'okela winners named". Honolulu Advertiser. October 29, 2006. Retrieved August 22, 2017.
  16. ^ Nakaso, Dan (May 26, 2011). "Shadow lessons: Educators will show kids and adults the marvels of a Lahaina Noon event". Honolulu Star-Advertiser. Archived from the original on August 4, 2011.

Further reading

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