Bob Moler's Ephemeris Blog

This is Ephemeris for Friday, September 18th. Today the Sun will be up for 12 hours and 22 minutes, setting at 7:47, and it will rise tomorrow at 7:26. The Moon, at first quarter today, will set at 11:40 this evening.

Tonight’s first quarter moon will appear low in the southern sky at its highest at about 11 minutes before sunset tonight. The moon is in the part of the sky where the sun will be on the first day of winter, December 21st at it’s lowest and the moon will be even lower tonight. For us, in Northern Michigan that’s 15 degrees, or one and a half times the width of a fist held at arms length. The moon, though, is even lower than the sun will be that day. The sun will be 22º above the southern horizon that day, a bit more than two fist widths above the southern horizon. I talk a lot about angles on this program, because measuring angles is what astronomers did before the invention of the telescope. A telescope allows better precision, among other attributes.

The astronomical event times given in this blog are for the Traverse City/Interlochen area of Michigan (Lat 44.7° N, Long 85.7° W; EDT, UT – 4 hours) unless stated otherwise. Times will be different for other locations.

Addendum

As readers of this blog may have surmised, I’m facinated by angles in the sky.