3I/ATLAS

Designation

3I/ATLAS was the third-ever interstellar object discovered passing through our Solar System. It was detected in July 2025 by the ATLAS (Asteroid Terrestrial-impact Last Alert System) survey in Chile. It shows clear cometary activity, with a glowing coma and tail.

At the time of its discovery, NSF–DOE Vera C. Rubin Observatory was just starting its commissioning observations, and scientists were able to recover earlier observations of 3I/ATLAS in Rubin data from 21 June. Those pre-discovery observations helped refine the comet’s trajectory and confirmed its cometary nature, offering an early preview of how Rubin’s 10-year survey will help us learn more about interstellar visitors from beyond our Solar System.

Diameter

0.60km 0.37mi

This object compared to other %category%

Average distance from the Sun

Semi-major axis (a)

Deviation from a circular orbit

Eccentricity (e)

Angle of orbit

Inclination (i)

Orbital elements

When will it be closest to the Sun?

days left

How far is it today?

From the Sun

1.00au

From the Earth