Overview
- 3I/ATLAS will make its closest approach to Earth on Dec. 19 at roughly 167 million miles (about 270 million kilometers), with agencies reiterating there is no impact risk.
- New Gemini North images from Nov. 26 show a post-perihelion shift to a faint green coma attributed to diatomic carbon, signaling fresh gases and potential for further outbursts.
- ESA’s XMM-Newton observed the comet for ~20 hours on Dec. 3, confirming low-energy X-ray emission consistent with solar-wind charge exchange; XRISM previously reported a tentative detection.
- Hubble’s late-November imaging and ground telescopes continue to show a sunward ‘anti-tail,’ which comet specialists describe as dust and ice behavior compatible with a natural comet.
- The U.N.-backed International Asteroid Warning Network has mobilized a record campaign, using the encounter as a planetary-defense tracking drill running through January 2026.