September 14-18, 2024: The Harvest Moon effect is observable during these five nights. This is the 4th full moon during summer.
by Jeffrey L. Hunt
Harvest Moon
This year’s Harvest Moon, the Full moon closest to the autumnal equinox occurs on the 17th at 9:24 p.m. Central Time.
Traditionally, the Harvest Moon’s light aided farming communities to collect the fields’ bounty at the end of the growing season. The extended moonlight at this season is from an astronomical effect.
During the summer season, the plane of the solar system, known as the ecliptic, that marks the track where the sun, moon, and planets appear, lies low in the sky after sundown, making shallow angles with the horizon in the east and west. This low angle affects Venus’ evening appearance.
From night to night during September evenings, the moon moves eastward approximately 13° against the stars, but not very far compared to the horizon. Its height is slightly lower from one evening to the next.
Delay of Moonrise
On average, the moon rises about 50 minutes later each night. As the moon approaches the Harvest Moon, the delay averages 20 minutes. The result is that the altitude changes little from night to night at the same time.
From September 14th through 18th, look for the moon each evening. Step outside an hour after sundown to see the Moon and Saturn in the same region of the sky.
Watch the Harvest Moon Effect
Here is what to see:
September 14: The bright gibbous moon, 87% illuminated, is about 20° above the south-southeast horizon. It is approaching Saturn, over 35° to the lower left.
September 15: The bright gibbous moon, 94% illuminated, is less than 20° above the southeast horizon at one hour after sundown. It is nearing Saturn, over 20° to the lower left.
September 16: The bright gibbous moon, 98% illuminated, stands above the east-southeast horizon, 5.5° to Saturn’s right.
September 17: The moon is over 10° above the east-southeast horizon and 9.8° to Saturn’s lower left. A partial lunar eclipse is at its maximum at 9:44 p.m. Central Time. The moon is near perigee – closest point to Earth – so this moon might be called “A supermoon blood moon” in the popular press. Early this morning, the moon occults or eclipses Saturn for sky watchers western North America and Hawaii.
September 18: The nearly-full moon is less than 10° up in the east, over 25° to Saturn’s lower left.
The moon has a busy astronomical week with an occultation, perigee, and a partial lunar eclipse.
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