3I/ATLAS

Interstellar comet that entered the solar system in 2025

3I/Atlas is an interstellar object. It is the third known object that has passed through our solar system from outside.[1]

The comet's icy core has a diameter of between 440 m (1,400 ft) and 5.6 km (3.5 mi).[2]

3I/ATLAS passed closest to the Sun on 29 October 2025, when it was 1.36 astronomical units (about 126 million miles) from the Sun. Its aphelion, or furthest point from the Sun, is unknown because 3I/Atlas comes from outside of the solar system.

References

  1. ↑ "NASA's Mars Spacecraft Capture Images of Comet 3I/ATLAS". NASA. 2025-11-19. Retrieved 2026-02-10.
  2. ↑ "3I/ATLAS Facts and FAQS". NASA. 2025-11-13. Retrieved 2026-02-10.