Monday, September 24, 2007

Harvest Moon

This is the time of Harvest Moon. Lots of people use the expression, but not many really know what it means. During the few days before and after the full moon that is nearest the autumnal equinox, moonrise occurs just a few minutes later each night. Since the near full moon rises shortly before or after sunset, farmers can use the light from the it to help them see while they are harvesting the crops in the fields. They essentially receive an extra hour or two of worktime which can really help them during this critical time.

The moon's position on the ecliptic is the reason behind all this. Normally, the moon rises 50 minutes later each night. However, due to the slope of the ecliptic in the sky in late September around 7 pm, the near full moon rises only 15 -20 minutes later, meaning that it is about the same height in the sky at the same time of day in late September. Farther north in Canada, the effect is more dramatic with the near full moon rising 5 minutes later for these next few nights.

For the record, the full moon is at 3:46 pm on Wednesday and the fall equinox was yesterday.

Such is the view from Earth....

1 comment:

Anonymous said...

Great job.

Ed Cabaniss
Holden Beach, NC