See the Sharpest Image Yet of an Interstellar Comet Passing Through the Solar System
Data from the Hubble Space Telescope unveils new information about this mysterious visitor
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Key takeaway: What is 3I/ATLAS?
This comet, discovered by the NASA-funded Asteroid Terrestrial-impact Last Alert System (ATLAS), was first detected 420 million miles from the sun on July 1.
The Hubble Space Telescope has captured a stunning image of a high-speed comet traveling through our solar system. Scientists say the comet poses no danger to the Earth, and Hubble’s observations will help them learn more about this interstellar visitor.
The image—the sharpest one yet of comet 3I/ATLAS—shows a teardrop-shaped cocoon of dust streaking from its icy nucleus, as well as a faint dust tail. Comets form these tails when they get close to a star, as they heat up their frozen materials and turn them into gas.
The diameter of the nucleus is likely between 1,000 feet to 3.5 miles across, according to a preprint study based on the Hubble data.
“No one knows where the comet came from,” says David Jewitt, the lead author of the study and an astronomer at the University of California, Los Angeles, in a statement. “It’s like glimpsing a rifle bullet for a thousandth of a second. You can’t project that back with any accuracy to figure out where it started on its path.”
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The comet is also remarkably speedy. Discovered on July 1 by the Asteroid Terrestrial-impact Last Alert System (ATLAS), it’s the fastest observed object to have originated outside of our solar system. It’s zipping by at 130,000 mph. The closest it will come to our planet is 1.8 astronomical units (about 170 million miles) away, and when it reaches its closest point to the sun around October 30, it’ll be near Mars’ orbit.
Scientists believe the comet’s speed is a sign of its age. That’s because objects traveling through space pick up speed thanks to the gravitational pulls of different stars and stellar nurseries, reports Ashley Strickland at CNN.
Matthew Hopkins, an astronomer at the University of Oxford and lead author of a separate preprint about 3I/ATLAS, tells the outlet that the comet’s velocity “is very useful to us in particular, as over the last few years me and my co-authors have been building a model that allows us to predict properties of [interstellar objects] such as their age and composition, just from their velocity.”
In their study, Hopkins and his co-authors conclude that given its velocity, the comet is likely over 7.6 billion years old, making it older than our solar system. They also add that it’s unlikely that the comet shares the same origins as two previously discovered interstellar objects: ‘Oumuamua, detected in 2017, and 2I/Borisov, detected in 2019.
More observations from Hubble and other surveying instruments will help scientists uncover even more about our extraterrestrial guest. Observations from the James Webb Space Telescope, TESS (Transiting Exoplanet Survey Satellite) and the Neil Gehrels Swift Observatory are all expected to be released, allowing scientists to refine their analyses.
“This latest interstellar tourist is one of a previously undetected population of objects bursting onto the scene that will gradually emerge,” Jewitt adds in the statement. “This is now possible because we have powerful sky survey capabilities that we didn’t have before. We’ve crossed a threshold.”
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