Overview
- During its close pass in August 2025, NASA radar failed to detect the object where predicted, prompting optical recovery that showed it was far from its expected position and starting the investigation into its true nature.
- Precision astrometry over decades revealed a small nongravitational acceleration about ten times larger than the maximum Yarkovsky effect possible for a ~380-meter body, a signal the team attributed to outgassing jets.
- Targeted deep imaging with the Canada-France-Hawaii Telescope, the ESO Danish Telescope and the Very Large Telescope captured a faint coma and a weak tail, and the object received the provisional comet name P/1998 SH2.
- Researchers say there is no imminent Earth impact risk from this object, but they warn the discovery shows outgassing can blur orbital forecasts and that continuous high-precision tracking plus deep follow-up imaging are needed for accurate hazard assessment.
- The case marks the first time scientists predicted cometary activity from anomalous motion and then confirmed it by observation, highlighting a population of ‘dark comets’ that may hide in asteroid catalogs and changing how astronomers will search for risky near-Earth bodies.