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Lahaina Noon
Mon May 17, 2004
Listen in RealAudio 
Lahaina Noon signals that shining moment when shadows from vertical objects
disappear. Hi, I'm Bryan Yeaton for The Weather Notebook.
The Earth's tropics lie between the Tropic of Cancer and Tropic of Capricorn -- at
twenty-three and a half degrees north and south respectively -- regions where the sun
stands directly overhead at some time each year.
As the sun moves northward from the Equator toward the Tropic of Cancer, it passes
directly overhead at all latitudes in between. When it reaches the Tropic of Cancer on
June 22, the farthest north it will appear overhead each year, it is the Summer Solstice.
On its return trip south, it will again pass overhead.
Among the U.S. states, only Hawai'i lies within the Tropics. Thus, on one day each May
and another each July, the sun will be directly overhead on the major islands of the
Hawai'ian chain. Some refer to this event as "shadow-less noon," but that is a bit of a
misperception. The sun does cast shadows, only not from objects that stand exactly
vertical, like flagpoles.
This event had no name until 1990 when Honolulu's Bishop Museum Planetarium
sponsored a naming contest. The winning entry: "Lahaina Noon." In Hawai'ian,
Lahaina means, "Cruel Sun."
Lahaina Noon only happens at "local solar noon," when the sun is at its zenith at each
specific location, rather than "clock noon," which is uniform across the islands.
With the extreme north-south extent of the island chain, the day of Lahaina noon differs
by about two weeks, falling first on the Big Island May 18th and latest on Kuai'i, May 31.
On the return trip, Kuai'i experiences its second Lahaina Noon on July 12, and Hawai'i
on July 24.
Thanks to our contributing writer, meteorologist Keith Heidorn. The Weather Notebook
is funded by Subaru of America and the National Science Foundation.
Today's Links
Lahaina Noon -- Bishop Museum Planetarium
http://www.bishopmuseum.org/planetarium/lahainanoon.html
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