12/22/2015 – Ephemeris – Welcome to winter, or summer if you’re down under
Ephemeris for Tuesday, December 22nd. The Sun will rise at 8:17. It’ll be up for 8 hours and 48 minutes, setting at 5:05. The Moon, 3 days before full, will set at 5:59 tomorrow morning.
Today is the first full day of winter. For folks south of the equator this is the first full day of summer. The Earth reached a point in its orbit where its north pole is tipped its furthest away from the Sun, and is in shadow in the middle of it’s six month night. We do see the Sun, though less than 9 hours of daylight, and to boot the Sun only rises 22 degrees above the horizon giving us the least amount of energy of any day of the year. Why did the ancients celebrate this time of year? That’s because the Sun had slowed and stopped its drift southward and was beginning to come back higher in the sky. They still had to go through the worst of winter, but the Sun was coming back. Spring and summer would eventually return!
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
The above chart shows the diurnal path of the Sun at the winter and summer solstices for Traverse City, MI near 45º north latitude. Peak Sun altitude at noon at the winter solstice is 22º, while it’s 69º at the summer solstice.