September's bright full moon will be rising tonight, called the Harvest Moon, or Hunter's Moon. The Harvest Moon this year will take place on the night of Sept. 18 to 19.
Tonight's full moon will be the closest to the autumn equinox, and will be rising just before sunset. "Ddepending on the year, [it] can come anywhere from two weeks before to two weeks after the autumnal equinox," reports EarthSky.
The term Harvest Moon was coined after farmers used the additional light from the autumn moon to work longer in the fields when there was no electricity at the time, according to Earth Sky.
NASA's Dr. Tony Phillips also write: "In the days before electric lights, farmers depended on bright moonlight to extend the workday beyond sunset. It was the only way they could gather their ripening crops in time for market. The full moon closest to the autumnal equinox became the Harvest Moon, and it was always a welcome sight."
Another theory as to why the moon could be called Hunter's Moon is that the Native Indians used the extra light to hunt.
The moon will be so bright tonight that the dark patches of the moon, called plains or maria in Latin, will be visible without binoculars.
The moon rises later each day because it orbits the Earth but the Harvest Moon is unique because the time difference between the moonrise on following evenings will be much shorter than average. According to NASA Science News, "Throughout the year, the moon rises, on average, about 50 minutes later each day. But near the autumnal equinox..the day-to-day difference in the local time of moonrise is only 30 minutes."
The Northern Hemisphere of the Earth will experience an equinox in September while the Southern Hemisphere sees an equinox in March.
Sometimes, the Harvest moon can also be a supermoon but unfortunately this year it will not. The last Harvest supermoon was in 2010 and the next one isn't expected until 2029.
The Harvest Moon will be bright all night from dusk till dawn tonight. But according to astronomers' definition of the full moon where the moon lies directly opposite the son for the month, the exact "full moon" moment will actually occur at 7:13 a.m. Thursdsay morning on September 19, 2013.
See a video of the glorious Harvest Moon from last year on September 29, 2012: