I was going to post yesterday about the second Lahaina Noon but it turns out I got the dates wrong. I finally found the Honolulu planetarium’s astronomical highlights, also known as ephemerides, for 2006. This year, instead of being on May 31st and July 12th, Lahaina noon happened a day earlier on May 30th and July 11th.
The dates for the solstices and equinoxes change up to a day from year-to-year, and Lahaina noon is directly related to those occurrances. In fact, I bet that on one day, the sun is a few hundredths of a degree south of the zenith at solar noon, and the next day it is a few hundredths of a degree north, and Lahaina Noon is just whichever day it is closest. By extension, for each given latitude, there must be one spot around the earth that experiences the exact Lahaina noon. Or for a given longitude, you could travel north or south a few hundredths of a degree to get the sun exactly overhead. I’ll have to research this some more.
As a side note, I keep calling it the Honolulu Planetarium, but its real name is the Jhamandas Watumull Planetarium at the Bishop Museum.