Watch interstellar comet 3I/ATLAS make its closest approach to Earth in free livestream tonight

Interstellar comet 3I/ATLAS, closest approach to the Earth: online observation – 19 Dec. 2025. – YouTube

Eager skywatchers will soon have front-row seats to a rare cosmic encounter as interstellar comet 3I/ATLAS makes its closest approach to Earth, and you can watch it happen live online tonight!

Comet 3I/ATLAS will make its closest approach to Earth at 1 a.m. EST (0600 GMT) on Dec. 19. At that time, it will be about 1.8 astronomical units away — roughly 168 million miles (270 million kilometers), nearly twice the average distance between Earth and the sun.

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A glowing comet nucleus and coma are visible to the lower left of an image against a black night sky, punctuated by numerous white points representing stars. A ghostly tail is visible extending diagonally from the nucleus to the upper right corner of the image.

Interstellar comet 3I/ATLAS captured by astronomer Gianluca Masi of the Virtual Telescope Project on Nov. 19. (Image credit: Gianluca Masi, Virtual Telescope Project)

Discovered in July 2025 by the ATLAS (Asteroid Terrestrial-impact Last Alert System) survey, 3I/ATLAS quickly captured the attention of both scientists and the public. It is only the third confirmed interstellar object ever detected passing through our solar system, following 1I/‘Oumuamua in 2017 and 2I/Borisov in 2019. Researchers are especially interested in its composition and behavior, which could offer rare clues about how planetary systems form around other stars.

The comet is too faint to be seen with the naked eye and will be challenging even for small backyard telescopes. Under dark skies, observers with a telescope of 8 inches or larger may be able to spot it as a faint, fuzzy patch of light. If you’re unable to look for the comet in person, you can sit back, relax and enjoy the view from the comfort of your own home via the livestream.