3I/ATLAS has now made its closest approach to the sun and Earth and is now heading back out toward the outer solar system.

The interstellar comet 3I/ATLAS made its closest approach to Earth today (Dec. 19, 2025).

Since then, space agencies and observatories around the world have trained their instruments on 3I/ATLAS to study it during its flyby—it’s a rare opportunity to examine material from outside our solar...