NASA Confirms 1998 SH2 Is a Comet After 2 Million-Mile Earth Flyby
Updated
Updated · NASA · Jul 16
NASA Confirms 1998 SH2 Is a Comet After 2 Million-Mile Earth Flyby
3 articles · Updated · NASA · Jul 16
Summary
Nature Astronomy research confirmed near-Earth object 1998 SH2 is a comet after telescopes captured a weak but clear tail during its August 2025 pass within 2 million miles of Earth.
Irregular motion first exposed the object’s identity: radar observers could not find 1998 SH2 where gravity-only models predicted, and precision astrometry showed nongravitational thrust consistent with outgassing.
Images from the 3.6-meter Canada-France-Hawaii Telescope, the 1.5-meter Danish Telescope, and ESO’s 8.2-meter Very Large Telescope provided the visible evidence, earning the object the comet designation P/1998 SH2.
NASA said the finding could help reclassify some dark comets and sharpen planetary defense, since continuous tracking can reveal cometlike perturbations that change near-Earth objects’ paths and impact risk.
If asteroids can secretly be comets, what other cosmic threats are we currently misidentifying?
After a 27-year mistake, can our planetary defense system protect us from disguised cosmic threats?
The 2025 Discovery of P/1998 SH2: Unveiling a Dark Comet and Rethinking NEO Threats
Overview
In August 2025, the Near-Earth Object 1998 SH2 was reclassified from an asteroid to a comet, now known as P/1998 SH2, after scientists detected a faint tail using advanced telescopes. This discovery began with subtle changes in its orbit, suggesting hidden outgassing, which was later confirmed through deep imaging. The event revealed that some objects previously thought to be asteroids may actually be weakly active comets, challenging traditional classifications. This breakthrough highlights the need for improved detection methods, such as infrared surveys, and prompts a reassessment of planetary defense strategies to better track and understand potential threats from space.