NEW YORK (AP) — The last supermoon of the year will shine soon in December skies.
The moon's orbit around the Earth isn't a perfect circle so it gets nearer and farther as it swings around. When a full moon is closer to Earth in its orbit, a so-called supermoon happens. It makes the moon look up to 14% bigger and 30% brighter than the faintest moon of the year, according to NASA.
Supermoons happen a few times a year in clusters, taking advantage of the sweet spot in the moon's elliptical orbit, and Thursday night's event is the last of three in a row in 2025.
The supermoon can be glimpsed in clear night skies without any special equipment. But it can be tough to discern the subtle change with the naked eye.
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Whether a supermoon or not, the moon also appears bigger when it's close to the horizon because of what's called the moon illusion. It's a strange visual trick that experts can't yet explain.
"When you have a supermoon, that effect is just slightly more striking," said astronomer William Alston with the University of Hertfordshire.
Tides could be slightly higher during a supermoon because the moon is closer to Earth, but again, the difference isn't very noticeable.