Space Mystery Solved! This “Asteroid” Was Actually a Secret Comet All Along
Quick Summary
For nearly 30 years, astronomers tracked a space rock they thought was an ordinary asteroid. But NASA scientists just proved it is actually a comet — one that hides its identity by having almost no visible tail. The discovery could help protect Earth from future space dangers.
What Happened?
Back in 1998, astronomers spotted a rocky object traveling through our solar system. They named it 1998 SH2. It looked like a plain, boring asteroid — a lump of rock drifting around the Sun every 4.5 years. No glowing tail. No cloud of gas. Just a rock.
For almost three decades, everyone assumed that was exactly what it was.
But something was always a little strange. When scientists tracked 1998 SH2’s path through space very carefully, they noticed something odd: it wasn’t moving quite the way a normal rock should. Gravity was supposed to be the only force pulling it along. But 1998 SH2 kept drifting slightly off course. It was getting little invisible pushes.
Scientists at NASA’s Jet Propulsion Laboratory (JPL) figured out the answer. The object is actually a comet! Comets are made of rock and ice. When the Sun warms a comet, trapped ice turns straight into gas and shoots out into space — kind of like a tiny invisible jet engine. That escaping gas gives the comet small but real pushes, making it move in a wobbly way that a solid rock never would.
But 1998 SH2’s ice jets are very, very faint. The outgassing is so weak that the comet produces almost no tail and no glowing cloud around it. This makes it a “dark comet” — a comet hiding in disguise as an asteroid. Scientists used some of the most powerful telescopes on Earth to finally confirm its secret identity. Their findings were published in the journal Nature Astronomy.
Since a dark comet was first spotted in 2016, scientists have now found about a dozen of them.
Why Does It Matter?
Knowing the difference between asteroids and comets really matters for keeping Earth safe. Comets behave differently than asteroids because of those tiny invisible gas jets. A comet’s path is harder to predict. If we ever needed to track a dangerous space rock headed toward Earth, knowing whether it is secretly a comet would help scientists calculate its true path much more accurately. It also teaches us that our solar system has many more surprises waiting to be discovered.
Big Words
- Asteroid — A rocky object in space, usually made of rock and metal, that orbits the Sun but is much smaller than a planet.
- Comet — A space object made of rock and ice. When it gets close to the Sun, ice turns to gas and creates a glowing tail.
- Dark comet — A comet that has almost no visible tail or glow, making it look like an ordinary asteroid until its unusual movement gives it away.
- Outgassing — When ice on a comet heats up and turns directly into gas that shoots out into space, giving the comet a tiny push.
- Astrometry — The science of very carefully measuring exactly where objects in space are and how they move.
Fun Fact
Comets can travel at speeds of up to 150,000 miles per hour — fast enough to travel from New York to Los Angeles in less than one second!
Think About It
If you were a space detective trying to figure out if a mystery object is an asteroid or a comet, what clues would you look for?
Sources
- NASA Jet Propulsion Laboratory — NASA Study Finds Near-Earth Asteroid Is Actually Comet
- Space.com — After nearly 30 years, NASA realized this near-Earth asteroid is actually a comet
- The Watchers — NASA study finds near-Earth asteroid is actually a comet, offering new clues for planetary defense
- Universe Today — Astronomers Catch a Dark Comet Red-Handed
- Nature Astronomy — Non-gravitational acceleration indicative of cometary activity of near-Earth object 1998 SH2 (July 10, 2026)