Discovery and Orbit of 3I/ATLAS
3I/ATLAS was discovered on July 1, 2025, by the Asteroid Terrestrial-impact Last Alert System (ATLAS). Its hyperbolic trajectory confirmed it as an interstellar visitor, not bound by the Sun's gravity.
The comet passed its perihelion, or closest point to the Sun, in late October 2025, which activated sublimation of its ices, creating a bright coma and tails visible from Earth.
Observations by NASA and ESA
NASA's Hubble Space Telescope reobserved 3I/ATLAS on November 30, capturing detailed images that help track its movement and analyze its physical properties.
ESA’s Juice spacecraft conducted a close observation on November 4, using multiple instruments to study the comet’s gas halo and outflow, providing data on its composition and activity post-solar approach.
Scientific Importance and Future Trajectory
3I/ATLAS’s composition is similar to Solar System comets, suggesting commonality in planetary system formation across the galaxy.
After its closest approach to Earth in mid-December 2025, the comet will continue its journey back into interstellar space, offering a rare glimpse into materials from another star system.