The last full moon of the summer will hang large in the sky Friday night, appearing slightly bigger than usual in a sign that autumn is almost here for the Northern Hemisphere. Known as the "harvest" full moon, the moon will be visible for the next few nights, marking the final full moon before the autumnal equinox, or the official start of fall on Thursday.
In the United States' Eastern Hemisphere, the moon will share the night sky with a faint "penumbral" lunar eclipse that occurs when the moon falls under the Earth's shadow. Stargazers in Europe, Asia, Africa and Australia will see the same sky. The event will not happen again until 2024.
The harvest moon rises at the same time every night for a few days, providing a last burst of light before the long and dark fall and winter nights in many parts of the world. The phenomenon gets its name from an era when farmers used the fall moon to help finish the harvest on time, according to Alan MacRobert, an editor at Sky &Telescopemagazine. It's also known as Hunter's moon, because it once helped hunters track game.
A good time to head outside to see the moon is about 7 p.m. Bring a telescope if you want to see some detailed craters.
This year's Harvest moon is also a supermoon, defined as a moon very close to its closest approach to Earth in a given orbit. Don't want to miss the night lit up? You can watch the eclipse and supermoon on slooh.com, the astronomy broadcast service.
"During our live broadcast, we’ll take a deep dive into the mechanics behind the lunar eclipse, exploring why they only happen at the Full Moon, and what separates this year’s Penumbral Eclipse with last year’s Total Lunar Eclipse. We’ll also be joined by our friends at the Old Farmer’s Almanac to learn more about the Harvest Moon, and the many traditions and festivals surrounding the harvest season," the site states.