Interstellar comet turns blue and brightens up near the Sun
Interstellar visitor 3I/ATLAS just pulled off a cosmic surprise: as it swung closest to the Sun on October 29, 2025, it suddenly got much brighter and turned blue—a color shift spotted by NASA and European satellites.
This unusual glow hints at gasses escaping from its surface, not just dust.
Unusual color shift
Unlike most comets, which get redder near the Sun, 3I/ATLAS's brightness shot up way faster than expected and its blue color suggests some wild chemistry or solar effects we don't usually see.
Scientists tracked all this even while it was hidden behind the Sun, thanks to special satellite eyes.
Closest approach to Earth
The object will pop back into view in late November and make its closest pass by Earth on December 19 (don't worry—it'll still be pretty far away).
Astronomers are excited to check it out with Hubble and James Webb telescopes to learn more about what interstellar stuff is really made of.