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NASA Sees 'Stunning Surprise' as Smashed Asteroid Grows a Twin Tail

The Didymos-Dimorphos system is showing off after NASA's DART spacecraft hit it.

Didymos-Dimorphos asteroid system appears a bright blue ball with streaking blue twin tails behind it against a dark background.
Hubble has spotted a twin tail as seen in this image from October 2022.
NASA, ESA, STScI, Jian-Yang Li (PSI)/Joseph DePasquale

It was the space impact celebrated around the world. The DART spacecraft blasted itself into an asteroid last month during NASA's ambitious planetary defense test mission. It was a smashing success, but new follow-up images are showing some unexpected behavior from the Didymos-Dimorphos asteroid system.

NASA and the European Space Agency released a new image from the Hubble Space Telescope on Thursday showing the double asteroid system has developed a twin tail, seen as two streaks extending backward from a bright ball of blue-tinged light. 

DART (Double Asteroid Redirection Test) made history on Sept. 26 when the spacecraft plunged into Dimorphos, a small moonlet in orbit around larger asteroid Didymos. It was a test to see if an impact like that could change the orbit of a space object. It worked, and it provides a blueprint for how humanity might deal with a dangerous asteroid that's on track to threaten Earth.    

Hubble and the James Webb Space Telescope got a good early look at the plumes of material ejected from the crash. Astronomers later used ground-based telescopes to observe the asteroid's lengthy tail, calculating it at around 10,000 kilometers (6,000 miles) long. The new Hubble look shows what's happened since. NASA called the development of a second tail of ejecta "a stunning surprise."

Hubble has revisited the asteroid system multiple times since the impact. The data shows the second tail formed sometime between Oct. 2 and Oct. 8. "The twin tail is an unexpected development, although similar behavior is commonly seen in comets and active asteroids," said NASA. 

Scientists are seeking to understand the aftermath of DART's work and are now delving into the mystery of the twin tail and how it developed. 

While there are no known asteroid threats to Earth in the near future, we have plenty of examples of the damage space rocks can do. DART's sacrifice is about being prepared, but the journey didn't end with the impact. Now researchers need to make sense of the asteroid's behavior and look at how that knowledge could be applied to protecting Earth.