Archive for December 20, 2019

12/20/2019 – Ephemeris – Winter arrives late tomorrow night

December 20, 2019 Comments off

Ephemeris for Friday, December 20th. Today the Sun will be up for 8 hours and 48 minutes, setting at 5:04, and it will rise tomorrow at 8:16. The Moon, 1 day past last quarter, will rise at 2:55 tomorrow morning.

Tomorrow will be the first day of winter, barely, since the moment of solstice will arrive at 11:19 p.m. If you’re south of the equator this is the first day of summer. The Earth reaches 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. The Sun for us is up only 8 hours, 48 minutes, 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. Spring and summer would eventually return!

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


Winter solstice

The sun’s daily path through the sky from horizon to horizon on the first day of winter, the winter solstice. Credit My LookingUp program.

December solstice

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

Solstice shadows

Comparison of shadows between winter and summer solstices. Note the angles are approximate.