Overview
- Russia’s Laboratory of Solar Astronomy reported the moment of closest approach at 07:16 Moscow time (04:16 GMT) on December 19, placing 3I/ATLAS 268,918,000 kilometers from Earth.
- Observations from Hubble, the James Webb Space Telescope, ESA’s JUICE, Mars orbiters, and major ground observatories captured images and spectra showing a coma, dual tails, and gases including water, carbon monoxide, and carbon dioxide.
- ESA Director Josef Aschbacher and NASA scientists rejected claims of an artificial origin, stating measurements are consistent with a fast-moving natural comet on a hyperbolic trajectory.
- Preliminary size estimates remain broad, with Hubble-constrained analyses suggesting a nucleus between roughly 440 meters and 5.6 kilometers across, and the comet was too faint to see without telescopes.
- Now outbound, 3I/ATLAS is being tracked for an expected flyby near Jupiter in March 2026 before it escapes back into interstellar space, with officials reiterating there is no hazard to Earth.