Lahaina Noon Today

This is the inaugural post for the “ephemerides” category:

Update: I was off by a day, Lahaina noon was May 30th this year. See my erratum.

Today at local noon (12:35 pm on the east coast of Kaua’i), the sun will be directly overhead, at a point properly called the zenith. It is commonly said the sun will cast no shadow, but in fact will cast shadows straight down and only perfectly vertical objects such as flag poles will have no shadow.

It turns out there was no scientific term for this occurence, and so the Honolulu Planetarium held a contest in 90’s and the name Lahaina Noon was chosen. Lahaina is a town on the dry south-facing coast of Maui where the sun is glaring, intense, and hot—the name itself means “cruel sun” (not to be confused with “mean sun“).

For the northern hemisphere, north of the tropic of Cancer: on the winter solstice, the sun rises and sets the furtest south and its elevation at noon is the lowest of the year; on the equinoxes, the sun rises due east and sets due west; on the summer solstice, the sun rises and sets the furthest north, and its elevation at noon is the highest of the year; in the tropics the summer solstice elevation is greater than 90° from the south horizon
Source: NASA, graphic by the aptly named David P. Stern (“star” in German)

The path of the sun across the sky is called the ecliptic and defines an ecliptic plane. The angle of the ecliptic plane is constant for a given location, but it “moves” north and south with the seasons. On the imaginary line of the tropic of Cancer, 23°30′ of latitude north, the ecliptic touches the zenith once per year on the day of the summer solstice. Further south, the ecliptic passes north of the zenith and the sun will shine from the north the whole day. Lying between 21°54’N and 22°14’N, Kaua’i sees Lahaina noon twice, on May 31st and July 12th. Note that the other inhabited Hawaiian islands are further south and therefore experience the first Lahaina noon earlier and the second later, giving them more days of northern sunshine.

For the foreign readers, Lahaina Noon is also an pun on the expression high noon which denotes solar noon, when the sun is highest and hottest in the sky. Hawaii is the only US state in the tropics and thus the only one where Lahaina Noon occurs. I suppose billions of people live in the tropics around the world and don’t find the event special enough to name it.

Update: here are my photos of vertical objects at today’s Lahaina Noon.

Pointing the camera straight down at my feet shaded by my body, and the chainlink fence nearby casts a shadow only a few inches wide
The pole of our clothesline is nearly vertical, or rather I missed the exact time by a few minutes.

Printed from: http://great-hikes.com/blog/lahaina-noon-today/.
© 2017.

3 Comments   »

  1. Mike says:

    A one or two day followup, showing same photos, at similiar time of day, but different shadow patterns would be an interesting comparison.

    Kudos on the post and photos….very interesting!

    Kind Regards,

    Mike

  2. Scott says:

    I’ve been fascinated with this phenomenon for a while. I’d like to plan a trip to observe it. Do you know of any place where future occurances are published? For other locations (Caribbean) as well?

  3. Very best site. Keep working. Will return in the near future.

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