Shadows run and hide at Lahaina Noon

Alex Dzierba, Jr. figured out a great way to capture  ”Lahaina (lah-HI-nah) Noon” in Honolulu on May 26. A level standing upright casts no shadow. Lahaina means “cruel sun” in the old Hawaiian language. Credit: Alex Dzierba, Jr.

Notice anything odd about this photo? It was taken earlier this week in Honolulu, Hawaii. The sun is out – you can see that – but something’s missing. Look around the bottom of the level … hmm, what’s happened to its shadow?

Land of enchantment and short shadows. This painting of the port of Honolulu was made in 1816 by Louis Choris

In Hawaii they have a special name for this time of hidden shadows – Lahaina Noon - and it happens every year in late May and mid-July. Shadowless conditions only occur when the sun is directly overhead, and Hawaii is the only U.S. state where you can experience it. Vertical objects that make contact with the ground cast none at all which is why people in Honolulu walk around staring at flagpoles on May 26.

Craig Miyamoto of Honolulu photographs his shadow under the Lahaina Noon sun on May 28, 2011. Miyamoto explains: “I don’t have a beach ball on my head. That’s my stomach that’s protruding out in front and my big ol’ butt hanging out the rear.” Click photo to go to Craig’s blog

The rest of us in 49 remaining states never get to see the sun pass overhead because we’re all too far north. Even Key West, Florida. Only in the tropics does the sun ever sit directly on top of your head during the noon hour. Just the thought of it makes me sweat.

The sun’€™s position at noon on the first days of winter, spring and summer 2013. The sun climbs upward or north starting on the first day of winter and reaches its maximum height above the horizon on the first day of summer. That’s when it’s closest to the zenith or overhead point. From lowest to highest, the sun’s position changes by 47 degrees over the year. Created with Stellarium

Specifically, any place with a latitude between 23.5 degrees north and 23.5 degrees south will see the sun beam from the zenith twice a year – the first time when it’s moving northward (higher) in the sky during spring and a second time when it’s dropping southward (lower) after the summer solstice.

This zone of latitude lies between the Tropics of Cancer and Capricorn. Some of you might remember those lines from that old grade school globe of the Earth. Besides making good book titles, they mark the location around the globe where the sun is directly overhead at noon on or around the winter solstice (Capricorn) and summer solstice (Cancer). Any city within that band will see the sun cross the zenith twice a year.

Everyone gets into the fun in a Lahaina Noon event at the Bernice Pauahi Bishop Museum on May 27, 2011. Click photo to find this year’s Lahaina Noon dates for locations in Hawaii. Credit: Bernice Pauahi Bishop Museum

23.5 degrees is a familiar number, right? That’s the angle at which Earth’s axis is tilted. Seen from our tipped planet, the sun travels from  23.5 degrees south of the celestial equator (an extension of the real equator into space) on the first day of winter to 23.5 north of the equator on the first day of summer. Add it up and you get 47 degrees or about five fists held at arm’s length against the sky. That’s the full range of the sun’s up and down movement in the sky over the course of a year.

Here in Duluth, Minn. at latitude 47 degrees north the sun never gets any closer than 26.5 degrees (47 minus 23.5 = 26.5) from the overhead point. That’s why power poles hold no allure in my town on June 21. Things are better in Key West where the latitude is 24.5 degrees. Let’s do the math again: 24.5 minus 23.5 = 1 degree. That’s darn close to the zenith with only a thin rim of shadow coating the edges of an old man’s cane.

If you live outside the tropics, you can determine how close the sun gets to your zenith by simply finding the difference between your latitude and 23.5. This works for all latitudes outside the tropics. For Honolulu, cozily situated at 21 degrees north latitude, Lahaina Noon will occur again on July 15. Cities farther north or south of the Honolulu experience the overhead sun a few days later in May and earlier in July.

At the north and south poles, even on the summer solstice, the sun never gets any closer than 66.5 degrees from overhead. Anyone wanting to celebrate Polar Noon would have to be content with the sun only 23.5 degrees above the horizon. Ah, but there’s compensation for this pitiful altitude – the sun’s up all night 6 months in a row.

Coming tomorrow: How to find asteroid 1998 QE2 when it passes Earth this weekend

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About astrobob

My name is Bob King and I work at the Duluth News Tribune in Duluth, Minn. as a photographer and photo editor. I'm also an amateur astronomer and have been keen on the sky since age 11. My modest credentials include membership in the American Association of Variable Star Observers (AAVSO) where I'm a regular contributor, International Meteorite Collectors Assn. and Arrowhead Astronomical Society. I also teach community education astronomy classes at our local planetarium.

17 thoughts on “Shadows run and hide at Lahaina Noon

  1. Hi Bob
    Thanks for a very interesting blog, I had never heard of that before, I know that we are lucky to get any sunshine at all in Scotland, UK, never mind Lahaina noon, but we can all dream :-) Thanks

  2. Aloha Astro Bob!

    Having lived in Hawaii for 24 years (and counting), I’ve often noticed how short or almost missing my shadow is during certain times of the year. Believe it or not, I’d never heard of it being called “Lahaina Noon” or anything until reading your article. Somehow I missed this “subject” over the years.

    Whenever I’d notice the “short shadows” all around, I’d flashback to my 7th grade geography class (in south Minneapolis) where I learned of this event happening in Ecuador. The geography book actually showed a picture of people there “standing” on their shadows.

    Thanks for continuing my education, Bob!

    Aloha For Now!

  3. Since the moon is tilted to the Earth’s ecliptic by 5.14 degrees, during the major lunar standstill, the moon can go overhead up to latitudes 28.5 degrees north or south of the Equator so although the sun never is directly overhead at these latitudes, the moon can be seen directly overhead in Central Florida and Southern Texas! Even during this time in New Orleans (at 30 degrees north), the moon – at it’s northern extreme – will only be 2 degrees away from the zenith. The flip side is that during a minor lunar standstill, however, the moon never goes more than 18.5 degrees north or south so ever the Tropic of Cancer and Hawaii will never see the moon overhead at this time.

  4. Sorry for the typo, I meant even when referring to the sentence the “even Tropic of Cancer and Hawaii will never see the moon overhead at this time”.

  5. Astrobob,

    Surely and logically, at any given location in the tropics, the sun can only be directly over one person’s head at any given time. Why is it that everyone seems to be standing with their shadow directly beneath them in the photo above with many people around the flagpole ?

    • Hi Robert,
      Good question. If the sun were closeby, say just a couple miles away, only one person would be standing in their shadow. All the other shadows would be angled this way and that. But because the sun is so incredibly far away (93 million miles) compared to the distances between the people, the shadows are essentially identical. Make sense?

  6. Astrobob,

    Two other very good points, as the sun is seen as a disk and not a point, part of the sun will be visible all night slightly south of the Arctic Circle and it will still look overhead even a mile north of the “defined Tropic of Cancer”, but it reality it will be off the zenith by about a few arc-minutes.

    The other point is that flagpoles and lampposts (and other vertical objects) do not cast a shadow when the sky is completely overcast, even when the sun is low in the sky!

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