The asteroid NASA crashed into looks like a comet now, with a forked tail, Hubble image reveals

• NASA's Hubble Space Telescope captured a comet-like forked tail streaming from the asteroid Dimorphos.
• NASA's DART spacecraft slammed into the asteroid in September, as practice for saving Earth.

The asteroid Dimorphos just hasn't been the same since NASA slammed a spacecraft into it. In fact, it kind of looks like a comet now, NASA discovered when the Hubble Space Telescope snapped a new image of the distant space rock.

NASA's Double Asteroid Redirection Test (DART) was a daring attempt to practice diverting an asteroid away from Earth. Astronomers don't know of any hazardous asteroids heading for Earth in the next 100 years, but the agency wants to be prepared in case it needs to nudge away Armageddon. So on September 26, the DART spacecraft slammed into Dimorphos, pushing it slightly closer to the larger asteroid it's orbiting, called Didymos.

An asteroid — a simple rock — usually appears as a point of light in telescope images. But a comet — a ball of ice and dust — usually has two distinct tails. One tail appears white and is made of dust. The other looks blue, since it's made of electrically charged particles called ions.

Thanks to the explosive DART impact, a stream of dust and rock has been drifting from Dimorphos out into space. Now it has the forked-tail appearance of a comet. That double tail is an "unexpected development," according to NASA's statement on the Hubble photo.

Hubble has observed the Dimorphos-Didymos system 18 times since DART's impact. The images indicate that the second, "northern" tail formed sometime between October 2 and 8. Scientists aren't sure how it happened, according to NASA, but will continue investigating in the coming months.

By gathering as much data as possible about the DART impact, and what happened to Dimorphos afterward, will help NASA plan for any future mission to deflect a dangerous asteroid. Telescopes across the planet and throughout Earth's orbit, including the new James Webb Space Telescope, are watching the asteroid closely.