Overview
- The object long tracked as asteroid 1998 SH2 failed to appear at its predicted location during the Aug. 28, 2025 close approach, alerting astronomers to an unexpected orbital deviation.
- Precision astrometry showed nongravitational accelerations consistent with weak outgassing, leading JPL navigation engineer Davide Farnocchia and colleagues to suspect cometary activity.
- Deep follow-up imaging from the Canada‑France‑Hawaii Telescope, ESO’s Danish Telescope and the VLT revealed a faint tail and coma, and the object has been given the provisional comet name P/1998 SH2.
- The peer‑reviewed study was published in Nature Astronomy on July 16, 2026, and the authors say there is currently no indication that P/1998 SH2 poses an Earth impact threat.
- Researchers say the case highlights a hidden class of 'dark comets' that can masquerade as asteroids, complicating long‑term orbit forecasts and strengthening calls for continuous precision tracking and next‑generation surveys such as NEO Surveyor.