3I/ATLAS Flyby

Attention grabbing interstellar visitor 3I/ATLAS made its not-so-close flyby of our fair planet on December 19 at a distance of 1.8 astronomical units. That's about 900 light-seconds. This deep exposure captures the comet from another star system as it gently swept across a faint background of stars in the constellation Leo about 4 days earlier. Though faint, colors emphasized in the image data show off the comet's yellowish dust tail and bluish ion tail along with a greenish tinged coma. And even as it is scrutinized by arrays of telescopes and spacecraft from planet Earth, 3I/ATLAS is headed out of the Solar System. It's presently moving outward along a hyperbolic trajectory at about 64 kilometers per second relative to the Sun, too fast to be bound by the Sun's gravity.

NASA Astronomy Picture of the Day 2025-12-26 Open Image in HD