Comet 3I/ATLAS's closest approach: NASA’s December 2025 skywatching tips

Interstellar comet 3I/ATLAS will be hot news this December as it will be making its closest approach to Earth. The event is set to take place on the 19th of the month, when the comet will be around 170 million miles away from our planet, according to NASA. The comet poses no threat to Earth and will be at more than 700 times the distance between the Earth and the Moon. With it being the third known object to come from outside the system, NASA continues to observe and study the comet. A variety of spacecraft and telescopes, both on the ground and in orbit, are focused on the object.

NASA said that despite the distance, skywatchers can catch the comet, looking east to northeast in the early pre-dawn morning. The comet will be just below Regulus, a star at the heart of the constellation Leo. To catch a glimpse before it makes its way out of the system, one must look through a telescope with an aperture of at least 30 centimeters. 

Among the space agencies tracking the interstellar visitor is also the ESA, whose Planetary Defence Office used data from the ExoMars Trace Gas Orbiter to predict its trajectory and location with tenfold accuracy. ESA’s study was part of a broader mission to detect, track, and characterize near-Earth objects. The TGO data was combined with Earth-based telescope data to improve the predictions of the comet’s path.

ESA's Jupiter Icy Moons Explorer (Juice) also observed the comet following its closest approach to our Sun. The data from Juice, however, will take time to reach us and is not expected before February 2026, per the ESA.

Meanwhile, NASA, which could not release its data on 3I/ATLAS during the 43-day government lockdown, held a much-awaited briefing on November 19 to release exclusive images of the comet. The images were taken by a number of the agency's missions and telescopes, including the James Webb Space Telescope, the Perseverance Mars rover, the Mars Reconnaissance Orbiter, along with the Lucy and Psyche asteroid probes. "It's a rare opportunity to compare ancient dust from a distant solar system to that from our own," said the acting director of NASA's Astrophysics Division, Shawn Domagal-Goldman.

The last month of the year has more to offer than the close approach of the comet 3I/ATLAS. The Moon and Jupiter will meet for a conjunction on December 7. All you need to do is look up towards the eastern sky on the day, and you'll find the gas giant either above or to the right of our natural satellite. Then there is the Geminid meteor shower that will peak on the 13th and 14th of the month. One of the best and most reliable annual meteor showers, it is composed of debris from the asteroid 3200 Phaethon. If you are lucky enough to set up camp underneath a particularly dark patch of sky, you might just catch up to 120 Geminid meteors an hour!

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