Bob Moler's Ephemeris Blog

This is Bob Moler with Ephemeris for Thursday, October 5th. The Sun will rise at 7:45. It’ll be up for 11 hours and 29 minutes, setting at 7:15. The Moon, at full today, will rise at 7:38 this evening.

This is the day of the Harvest Moon. It will rise just before sunset and colored like a huge pumpkin. The huge size is an optical illusion, and the coloring is courtesy of our Earth’s atmosphere selectively bleeding out the blue from the Moon’s light. The reason the Harvest Moon is so special is that during this period the Moon rises for quite a few days just before and in twilight, effectively lengthening the hours of light that farmers can have to harvest their crops. Tomorrow the Moon will rise 32 minutes later than tonight, rather than the average 50 minutes. The effect is a bit diminished this year because the Moon is nearing perigee, its closest to the Earth and is traveling a bit faster than average. The Moon can get down to a 25 minute day-to-day difference.

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

Addendum

The position of the Moon for 7 nights centered on moon rise tonight (10/04/2017). The rotation of the Earth carries the Moon to rise parallel to the green celestial equator line. The brown area at the bottom is below the horizon. Click on the image to enlarge. Created using Cartes du Ciel (Sky Charts).