Overview
- 3I/ATLAS, the third confirmed interstellar visitor, is currently behind the Sun and heads for perihelion on October 29.
- Keck II observations reported a pronounced sunward anti-tail and detections of cyanide and nickel emissions, features experts say can arise from large dust grains and viewing geometry.
- An arXiv study accepted by Research Notes of the AAS projects that ESA’s Hera and NASA’s Europa Clipper will pass downwind of the ion tail between October 25–November 1 and October 30–November 6, respectively.
- Europa Clipper carries a plasma instrument and magnetometer suited to detect tail ions and magnetic draping, whereas Hera lacks the sensors, with both spacecraft expected to miss the tail axis by about 8 million kilometers.
- Some commentators promote a technological-origin scenario to be ‘tested’ at perihelion, but NASA and most comet specialists assess 3I/ATLAS as an unusual yet natural comet, with Mars orbiters and possibly Juno and Juice providing complementary observations.