Overview
- 3I/ATLAS is the third confirmed interstellar visitor to the Solar System, discovered by the ATLAS survey in mid‑2025.
- ALMA measured peak methanol outgassing of up to 2.9 × 10^26 molecules per second near perihelion in late October 2025.
- The methanol-to-hydrogen cyanide ratios of 79 and 124 rank among the highest recorded in any comet, signaling a distinct chemical history.
- Spectral mapping indicates HCN originates primarily from the nucleus while a significant share of methanol is released from coma grains over 258 km from the core, implying a heterogeneous body.
- The object, several kilometers across, has passed perihelion and is now outbound as teams analyze post‑perihelion data, with claims of artificial origin widely disputed by scientists.