ABOVE: The trajectory of interstellar comet 3I/ATLAS as it passes through our solar system. Credit: NASA/JPL-Caltech
A University of Hawaiʻi-operated telescope has discovered the third known interstellar object to visit our solar system. Dubbed 3I/ATLAS, this cosmic backpacker is thought to be a comet measuring roughly 12 miles across. As of July 2025, the comet is blazing through our cosmic neighborhood toward the Sun at more than 150,000 mph and is anticipated to make its closest approach to our star in October.
Astronomers say that if 3I/ATLAS were to collide with Earth, it would produce an explosion 100 times greater than the asteroid that killed off the dinosaurs. Thankfully, itʻs passing at a safe distance from Earth and poses no threat.
3I/ATLAS is the third known interstellar visitor following the discoveries of ʻOumuamua in 2017 and comet 2I/Borisov in 2019.