Bob Moler's Ephemeris Blog

Ephemeris for Friday, December 21st. The Sun will rise at 8:16. It’ll be up for 8 hours and 48 minutes, setting at 5:05. The Moon, 1 day before full, will set at 7:56 tomorrow morning.

Today is the shortest day of the year, well in daylight hours. The Sun will be up for only 8 hours and 48 minutes in the Interlochen/Traverse City area, 8 hours 53 minutes in Ludington, and 8 hours 40 minutes at the Straits. This is because the northern end of the Earth’s axis is pointing some 23 and a half degrees away from the Sun. Or it will at 5:22 this afternoon, the instant of winter solstice, when winter will begin. To find how high the Sun will get in the south at local noon take 90 minus your latitude and subtract also 23 and a half degrees. For Interlochen that’s 21.8 degrees above the southern horizon. We’re not getting much heat from the Sun. But as winter progresses the rising Sun will slow the cooling and begin to warm us up before spring.

The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.

Addendum

The Earth and its axis on the first day of winter, the winter solstice. From my Sun and the Earth talk slides.

DSCOVR satellite’s Earth Polychromatic Camera image of the Earth at 18:09 UTC (1:09 p.m.) December 19, 2017. We’re way up at the top just under the clouds at the top. It was actually partly cloudy that day. The DSCOVR satellite was in a halo orbit about the Earth-Sun Lagrange L1 point, 934,498 miles (1,503,929 km) toward the Sun from Earth.

Comparing the sun’s path at the summer and winter solstices for Interlochen/Traverse City. This is a stereographic representation of the whole sky which distorts the sky and magnifies the size of the sun’s path near the horizon.