The Geminids are one of the best meteor showers of the year—and the weirdest. Here’s how to see them
This December's dazzling display comes from a strange asteroid with comet-like behavior—and a tail of debris that astronomers say shouldn’t exist.
The year’s most dazzling meteor shower is almost upon us. The Geminids, known for bright, colorful shooting stars, will peak on the night of December 13 into the morning of December 14. Under perfect viewing conditions, the Geminids deliver up to 120 meteors per hour, though factors like light pollution and atmospheric conditions can reduce that number.
But unlike most meteor showers, the Geminids don’t come from a comet. They’re created by debris from 3200 Phaethon, a strange asteroid that brightens and grows a faint tail, helping make this shower especially bright.
Here’s everything you need to know about the Geminids and Phaethon 3200—and how to see the meteor shower this year.
What are the Geminids?
Most meteor showers occur when Earth passes through debris trails shed by orbiting comets— the bits of ice and dust burn up in our atmosphere, producing shooting stars. Conceptually, the same process creates the Geminids. But instead of passing through a comet’s tail, Earth passes through the trail of Phaethon 3200, which sheds larger, tougher, and rockier debris than comets.
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“This material is larger on average and survives further into our atmosphere and tends to produce brighter meteors,” says Rubert Lunsford, the journal editor of the American Meteor Society. Phaethon 3200’s debris also contains more metal. “When these metals are heated during the passage through our atmosphere, they produce colors associated with each type of metal,” he adds. Calcium and silicon produce orange; iron and sodium produce yellow; nickel produces green; and magnesium produces blue.
What is Phaethon 3200?
It’s a comet! It’s an asteroid! It’s…Phaethon 3200? This rocky object straddles the line between a comet and an asteroid, though most astronomers consider it the latter. “Phaethon is an approximately six-kilometer-diameter asteroid that passes very close to the sun, within half the distance of Mercury,” says Qicheng Zhang, an astronomer at Arizona’s Lowell Observatory. Such orbits are far more common to comets than asteroids.
Phaethon displays other cometary characteristics, too. Most notably, it brightens and forms a small tail as it approaches the sun. But because Phaethon 3200 is rocky, not icy, that tail shouldn’t exist. However, in a 2023 study, Zhang and colleagues discovered that the tail is composed of sodium gas instead of the vaporized dust found in comets’ tails.
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Yet this tiny sodium tail can’t explain the dense stream of debris that produces the Geminids. Zhang proposes two hypotheses for the Geminids stream. While Phaethon 3200 “currently outgasses sodium at a low rate when closest to the sun, it might have done so more strongly in the past, or there might be other gases. Outgassing would lift dust off the surface, like a comet,” he says. Or, he posits, “[a]symmetric outgassing or thermal radiation could have spun up the asteroid until centrifugal forces exceeded its gravity, partially breaking it apart.”
Given its strange combination of characteristics, Phaethon 3200 might not be an actual asteroid at all, but rather a dead comet or a rock comet. Whatever it is, it’s responsible for one of the sky’s most spectacular annual shows.
How to see the Geminids in 2025
Provided the weather cooperates, there will be solid viewing conditions for the Geminid meteor shower this year. During the peak from the night of December 13 to the morning of December 15, the waning crescent moon will be about 25 percent illuminated, and it will rise around 2 a.m. local time.
“Potential observers have the choice to observe prior to moonrise or to look toward the west with the moon at their back after 2 a.m.,” says Lunsford. “Since the strongest rates occur near 2 a.m., most people will face eastward before that time, then swing around to the west after it to avoid having the moonlight affect their night vision.”
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For most stargazers, it’s best to start looking up around 10 p.m., when the radiant, or point from which the meteors appear to emanate—in this case, the constellation Gemini—climbs high and the sky remains moon-free. Bring a reclining chair, dress warmly, and give your eyes at least 20 to 30 minutes to adapt to the darkness. Then enjoy the show.
