Astronomers have confirmed the discovery of a third interstellar object hurtling through our solar system, a colossal comet designated 3I/Atlas, likely the largest ever detected from beyond our stellar neighbourhood.
This icy interloper offers a rare glimpse into the composition of other star systems.
First spotted on Tuesday by the National Aeronautics and Space Administration (Nasa)-funded ATLAS survey in Hawaii, the object, originally known as A11pl3Z, was quickly confirmed to be of interstellar origin by the International Astronomical Union’s Minor Planet Center, Science Alert reported.
Its “fuzziness” strongly suggests it’s primarily composed of ice rather than rock, said Jonathan McDowell, an astronomer at the Harvard-Smithsonian Center for Astrophysics.
The good news for Earthlings is that 3I/Atlas poses no threat to our planet.
Richard Moissl, head of planetary defence at the European Space Agency, confirmed it will “fly deep through the solar system, passing just inside the orbit of Mars” without impacting any of our planetary neighbours.
Scientists are buzzing with excitement as they refine calculations, which currently indicate the object is rocketing through space at over 60 kilometres (37 miles) per second. This astounding speed confirms its unbound trajectory, signifying it’s not orbiting our Sun but rather traversing interstellar space before continuing its journey.
“We think that probably these little ice balls get formed associated with star systems,” McDowell elaborated, “And then as another star passes by, tugs on the ice ball, frees it out. It goes rogue, wanders through the galaxy, and now this one is just passing us.”
Professional and amateur astronomers worldwide have delved into past telescope data, tracing the comet’s path back to at least June 14.
Current estimates place its size at roughly 10-20km wide, potentially making it the largest interstellar visitor ever detected, though its icy composition could make it appear larger due to increased light reflection.
The comet is expected to brighten and draw closer to the Sun until late October, remaining observable by telescope until next year, Moissl added.
This marks only the third instance humanity has detected an object entering our solar system from beyond.
The first, ‘Oumuamua, was discovered in 2017 and sparked theories of alien origin before being reclassified. The second, 2I/Borisov, was spotted in 2019.
Mark Norris, an astronomer at the UK’s University of Central Lancashire, noted that 3I/Atlas appears to be “moving considerably faster than the other two extra-solar objects that we previously discovered.”
Currently, the object is roughly the distance of Jupiter away from Earth and is only visible in the Southern Hemisphere.
While a mission to intercept 3I/Atlas is not currently feasible, these rare cosmic visitors provide scientists with an unparalleled opportunity to study material from outside our solar system.