Tonight, at 7 minutes past midnight, the sun in its path will be exactly over the equator.
The longest day here at a latitude of 8 degrees, 40 minutes north of the equator is 12 hours, 22 minutes. The shortest day is 11 hours, 47 minutes. Thus, the difference between the longest and shortest days is 1 hour, 37 minutes.
I’m getting this information from the US Naval Observatory after having punched in the latitude and longitude for our location near Potrerillos Arriba. While studying this table, I saw that sunrise and sunset times are not exactly 12 hours apart on the day of the equinox. For Potrerillos, the day when sunrise is 6:41 AM and sunset is 6:41 PM is on March 6 (and 7).
I thought I’d have to do a lot of research to figure this one out.
But one quick look at Wikipedia explained it. (And then I thought, of course!)
At sunrise, the center of the sun is below the horizon, so we’re seeing the sun before its center is exactly on the horizon. At sunset, the center of the sun is once again below the horizon, so we’re seeing the sun after its center is exactly on the horizon. At equinox, the center of the setting sun should cross the horizon exactly 12 hours after the center of the sun crossed the horizon when rising. I suppose you could say we see the sun for a little while both before and after the sun crosses the equator.
For us folks here in Potrerillos, the sun is in the sky for 12 hours and 4 minutes today. This means that we saw the sun for about 2 minutes this morning before the sun crossed the horizon and we’ll continue to see it for about 2 minutes this evening after it has already crossed the horizon. We won’t see it at the moment it crosses the equator, but, hey!
