A space object long believed to be a near-Earth asteroid has been reclassified after NASA scientists discovered it behaves more like a comet. The finding sheds new light on a rare category of celestial objects known as dark comets and could improve future efforts to track potentially hazardous objects near Earth.
NASA Reclassifies 1998 SH2 as a Dark Comet
The object, known as 1998 SH2, was first identified in 1998 and spent nearly three decades classified as an asteroid. However, during a close approach to Earth in August 2025, researchers observed unexpected changes in its trajectory.
Scientists found that the object’s movement through space could not be explained by gravity alone. After reviewing decades of observational data, they concluded that a small amount of gas escaping from the object’s surface was subtly altering its orbit.
This type of behavior is commonly associated with comets, which release gas and dust as solar heating causes frozen material to vaporize.
Powerful Telescopes Confirm Comet Activity
To investigate further, astronomers used some of the world’s most advanced telescopes, including observatories in Hawaii and Chile. Their observations eventually revealed a faint tail extending from the object.
The discovery confirmed that 1998 SH2 is not simply an asteroid but a comet. As a result, it has received the additional comet designation P/1998 SH2.
While many people associate comets with bright, dramatic tails visible in the night sky, this object is far less conspicuous.
What Is a Dark Comet?
1998 SH2 belongs to a rare class of objects known as dark comets. These bodies display comet-like activity but release such small amounts of gas and dust that they often appear indistinguishable from ordinary asteroids when viewed through telescopes.
Because their activity is so subtle, dark comets can remain misclassified for years or even decades. Researchers believe additional objects currently listed as asteroids could ultimately prove to be members of this unusual category.
The discovery adds to a growing scientific effort to better understand the diversity of objects orbiting within the solar system and crossing Earth’s neighborhood.
Implications for Planetary Defense
The reclassification of 1998 SH2 has significance beyond astronomy. NASA scientists say accurately determining whether a near-Earth object is an asteroid or a comet is critical for predicting how its orbit may change over time.
Even small amounts of gas released from an object’s surface can gradually alter its path, making long-term tracking more complex. Understanding these changes helps researchers refine impact-risk assessments and improve planetary defense strategies.
“This work shows the importance of continuously tracking near-Earth objects,” said Davide Farnocchia, a navigation engineer with NASA’s Center for Near-Earth Object Studies at the Jet Propulsion Laboratory.
“Detecting these perturbations can be an important diagnostic tool for planetary defense that will help understand which objects may be comets rather than asteroids, how their orbits evolve, and how that influences their Earth impact risks.”
Future Missions Will Expand Detection Efforts
NASA says its upcoming Near-Earth Object Surveyor mission is expected to strengthen the agency’s ability to identify difficult-to-detect objects, including dark asteroids and dark comets.
The space-based observatory will be designed to search for and track objects that could pose potential risks to Earth, while also helping scientists better understand the composition and behavior of small bodies throughout the solar system.
Looking Ahead
The discovery that 1998 SH2 is actually a dark comet highlights how much remains unknown about the objects traveling through Earth’s cosmic neighborhood. As NASA continues to improve its monitoring capabilities, researchers expect to uncover more hidden comet-like objects, providing valuable insights into both solar system science and planetary defense efforts.
Ambrose Sherman writes for Hardwood Paroxysm, covering news, politics, business, technology, sport, entertainment, and lifestyle. He focuses on clear reporting, current affairs, and stories that matter to readers, providing reliable information in an accessible and engaging way.
