December 2025 astronomy guide: Supermoon, Geminids and the month’s best sky events
From a bright supermoon to the Geminid meteor shower, December is filled with must-see astronomy events. Here's when and how to see each celestial sight.
From the best meteor shower of the year, the Geminids, to the changing seasons on the solstice, here are the top astronomy events to mark down on your December 2025 calendar.
The final month of 2025 will bring a mix of celestial light shows and long winter nights, including one of the most highly anticipated meteor showers of the year. Here are the top events to mark on your calendar.
Supermoon: Dec. 4–5
The last full moon of the year will be a supermoon, appearing slightly larger and brighter than usual when it rises on the night of Dec. 4-5.
December’s full moon will be brighter because it occurs as the moon nears its closest point to Earth in its orbit. On average, the moon is 238,855 miles from Earth, but on Dec. 4, it will be about 17,000 miles closer.
The moon rises over mountains on Tuesday, Feb. 15, 2022, in the Yanqing district of Beijing. (AP Photo/Dmitri Lovetsky)
December’s full moon is traditionally known as the Cold Moon, a name tied to the arrival of Arctic air across North America. Other nicknames for the final full moon of the year include the Winter Maker Moon, the Long Night Moon, the Moon of the Popping Trees and the Little Spirit Moon — all reminders of the season’s chill and long nights.
Geminid meteor shower: Dec. 13–14
The Geminids are December’s headliner and one of the best meteor showers of the entire year.
The display peaks on the night of Saturday, Dec. 13, into the early hours of Sunday, Dec. 14. From a dark location, observers could see more than 100 meteors per hour.
In this Dec. 14, 2023 photo provided by NOIRLab, meteors from the Geminid meteor shower streak across the sky above the Nicholas U. Mayall Telescope at Kitt Peak National Observatory (KPNO), a program of the National Science Foundation's NOIRLab, located about 56 miles (90 kilometers) southwest of Tucson in the Tohono O'odham Nation. (NSF/NOIRLab via AP, File)
Unlike most meteor showers, the Geminids start early in the evening, making them easier to see for families and casual observers. The best viewing window will be after 10 p.m. local time when the shower's radiant point climbs high in the sky and before 2 a.m. local time when the moon rises and starts to brighten the sky.
Comet 3I/ATLAS close approach: Dec. 19
An interstellar comet is about to make its closest approach to Earth before it races out of the solar system, never to return.
“Comet 3I/ATLAS is making its closest approach to Earth on Dec. 19,” NASA’s Jet Propulsion Laboratory said. “This could be your best bet to see this interstellar interloper.” At its closest, it will still be roughly 170 million miles from Earth, more than 700 times farther away than the moon.
A skychart showing where Comet 3I/ATLAS will appear on Dec. 19, 2025. (NASA/JPL)
To spot the comet, skywatchers will need a telescope and a clear view of the eastern sky near the constellation Leo. Around 1 a.m., local time, on Dec. 19, it will appear in line with Jupiter and Regulus.
Winter solstice: Dec. 21 at 10:03 a.m. ET
Winter officially begins in the Northern Hemisphere on Sunday, Dec. 21, at 10:03 a.m. ET, marking the year’s December solstice. South of the equator, the same date signals the start of summer.
At that moment, the Northern Hemisphere is tilted farthest from the sun, bringing the shortest day and longest night of the year.
While the solstice marks the start of astronomical winter, meteorological winter begins on Dec. 1.
Ursid meteor shower: Dec. 21–22
The year ends with the Ursids, a smaller meteor shower that peaks on the night of Dec. 21–22 — the first night of astronomical winter following the solstice.
This final meteor shower of 2025 usually produces around 10 meteors per hour, though it benefits from long, dark nights at this time of year. The best chance to spot the Ursids will come late at night and before dawn, when the radiant near the constellation Ursa Minor climbs higher in the northern sky.
While the Ursids are far less active than the Geminids, they're still worth a look as it will be one of the final meteor showers for months. After the short-lived Quadrantids peak in early January, the next meteor shower does not take place until April.
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