Overview

• ESA’s Mars Express and ExoMars Trace Gas Orbiter are observing 3I/ATLAS during its Mars passage from October 1–7, with a closest separation of about 30 million kilometers on October 3.
• The comet is currently on the far side of the Sun from Earth and will reach perihelion around October 29–30 at roughly 1.4 AU, just inside Mars’s orbit.
• Very Large Telescope spectra report strong nickel emission in the coma with iron appearing only closer to the Sun, an anomalous metal ratio compared with known comets.
• Astronomers have logged rapid brightening and other atypical behavior, including reports of a sunward-pointing tail and an unusual CO2-to-water mix.
• NASA and ESA say the object poses no threat to Earth—closest approach is about 1.8 AU—and radio searches have not confirmed any emissions despite historical Wow! signal comparisons.