What time will interstellar comet 3I/ATLAS be closest to Earth tonight?

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.

Discovered on July 1, by NASA-funded ATLAS telescopes in Chile, 3I/ATLAS is only the third known interstellar object ever detected passing through our solar system, following ‘Oumuamua in 2017 and 2I/Borisov in 2019.

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.