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 will make its closest approach to Earth early on Friday, Dec. 19. While it won't come close enough to pose any risk to our planet, astronomers have calculated the precise moment when the comet reaches its minimum distance to us.

According to the orbital calculations from NASA's Jet Propulsion Laboratory (JPL) Horizons system, comet 3I/ATLAS will be closest to Earth at 1 a.m. EST (0600 GMT) on Dec. 19. At that time, the comet will be 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.18-19 on Space.com courtesy of the Virtual Telescope Project. The livestream will begin at 11 p.m. EST on Dec. 18 (0400 GMT on Dec. 19), 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.

Daisy Dobrijevic joined Space.com in February 2022 having previously worked for our sister publication All About Space magazine as a staff writer. Before joining us, Daisy completed an editorial internship with the BBC Sky at Night Magazine and worked at the National Space Centre in Leicester, U.K., where she enjoyed communicating space science to the public. In 2021, Daisy completed a PhD in plant physiology and also holds a Master's in Environmental Science, she is currently based in Nottingham, U.K. Daisy is passionate about all things space, with a penchant for solar activity and space weather. She has a strong interest in astrotourism and loves nothing more than a good northern lights chase!

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