Bob Moler's Ephemeris Blog

This is Ephemeris for Thursday, September 28th. Today the Sun will be up for 11 hours and 52 minutes, setting at 7:29, and it will rise tomorrow at 7:38. The Moon, 1 day before full, will set at 7:43 tomorrow morning.

Tomorrow night’s full moon is the Harvest Moon. It is the most famous of the named full moons, and was very useful in the days before electric lights. The reason is that the Moon, around the time it is full, doesn’t advance its rising time very much from night to night, effectively adding its light to twilight to allow more time to gather in crops. This is because the Moon is moving north as well as eastward. The farther north it is, the longer it stays up and retards the advance in rise times. On average, the Moon rises 50 minutes later each night. This week, the interval is down near 22 minutes advance in moonrise times per day, extending twilight and the amount of time each day to harvest the crops for a few more days.

The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EDT, UT –4 hours). They may be different for your location.

Addendum

My interest in the Harvest Moon is not in harvesting the crops. I just have a little garden, so it doesn’t take that long to pick tomatoes or whatever. But as an amateur astronomer I’m more interested in deep sky objects than I am in planets. Deep sky objects or DSOs are objects beyond the solar system and are usually very dim, which requires dark skies to view them. Near the Harvest Moon and even in August near the full moon it takes nearly a week for that @#$%^&* Moon to get the heck out of the evening sky, so I don’t have to stay up till after midnight to see anything. That’s I why have this interest in the Harvest Moon. Know your enemy!