What time will interstellar comet 3I/ATLAS be closest to Earth on Dec. 19?

graphic showing earth on the left and interstellar comet 3I Atlas on the right — NASA JPL pinpoints the moment the interstellar visitor passes closest to our planet. (Image credit: Comet: NASA, ESA, STScI, D. Jewitt (UCLA). Image Processing: J. DePasquale (STScI)). Graphic created in Canva Pro.)

Interstellar comet 3I/ATLAS made its closest approach to Earth early on Friday, Dec. 19. While it didn't come close enough to pose any risk to our planet, astronomers have calculated the precise moment when the comet reached its minimum distance to us.

According to the orbital calculations from NASA's Jet Propulsion Laboratory (JPL) Horizons system, comet 3I/ATLAS was closest to Earth at 1 a.m. EST (0600 GMT) on Dec. 19. At that time, the comet was about 1.8 astronomical units away — roughly 168 million miles (270 million kilometers — or nearly twice the average distance between Earth and the sun.

While comet 3I/ATLAS will remain far too distant and faint to become a naked-eye spectacle as it passes Earth, its flyby is scientifically valuable because interstellar objects are so rare. Studying 3I/ATLAS near its closest approach provides astronomers with their best opportunity to examine material formed around another star, offering a fleeting glimpse into planetary systems beyond our own.

Skywatchers can also follow along with the flyby live online Dec.19-20 on Space.com courtesy of the Virtual Telescope Project. The livestream will begin at 11 p.m. EST on Dec. 19 (0400 GMT on Dec. 20), offering viewers a chance to see the interstellar visitor as it makes its closest approach to Earth, weather permitting.

Follow along with the latest 3I/ATLAS news with our live blog.

Editor's note: This article was updated at 1:30 a.m. EST (0630 GMT) to reflect the close approach that occurred as expected at 1:00 a.m. (0600 GMT) Dec. 19, 2025.

Daisy Dobrijevic joined Space.com in February 2022, having previously worked as a staff writer for All About Space magazine. She completed an editorial internship with BBC Sky at Night Magazine and worked at the National Space Centre, communicating space science to the public.

Daisy holds a PhD in plant physiology and a Master's in Environmental Science. Based in Nottingham, U.K., she covers all things space, with a special focus on solar activity and space weather. She also has a keen interest in astrotourism and is always on the lookout for the next northern lights adventure.

She will be a guest speaker aboard HX's Solar Eclipse Expedition in August 2026 and will join Hurtigruten as an onboard astronomer for a northern lights sailing in January 2027.