|December 21||7:16 AM||4:32 PM||9h 15m 18s|
|March 21||6:56 AM||7:09 PM||12h 13m 32s|
|June 21||5:25 AM||8:30 PM||15h 5m 45s|
|September 21||6:56 AM||7:09 PM||12h 13m 32s|
Sunrise - sunset - day length - civil twilight - astronomical twilight
Q: Why is there more than 12 hours of daylight on the equinox?
A: On these two days, the geometric center of the sun
is above the horizon for 12 hours, and one might think this would indicate that
the length of the day (hours of daylight) would be the same.
However, ‘sunrise’ is defined as the instant when the upper edge of the sun's disk becomes visible above the horizon – not when the center of the sun is visible. In the same sense, ‘sunset’ refers to the moment the upper edge disappears below the horizon. At both instances, the center of the sun is below the horizon, and therefore the equinox day lasts a little longer than 12 hours.