The longest day

So what's really the longest day of the year in Songkhla? This has been a matter of debate for several years now among the SH3 brain trust. Conventional wisdom says it should be the summer solstice, when the overhead sun reaches its northernmost point. Except does that hold true in the tropics?

Evidently, yes. Here, from a genuine pointy-headed astrophysicist on physicsforum.com:

Calculate the length-of-day ( LD ) by

cos(LD/2) = - tan(declination) tan(latitude)

LD is in degrees that can be converted to hours, min, sec

For locations north of EQUATOR the longest day of the year coincides with the summer solstice.

Don't believe it? Check it for yourself here. (To help you: the coordinates of Yardstick's house, our own equivalent of the Greenwich Royal Observatory, are N 07 12.062 E 100 35.784.) What you'll find is that this year, June 21, 22, and 23 tie for longest, at least when rounded to the nearest minute, at 12 hours and 33 minutes each.