There Might Be an Entire Orbit, Filled with Asteroids that Came from Outside the Solar System

An illustration of the orbit of a Centaur asteroid. Credit: Namouni and Morais, NASA

Aliens could be all around us. Lurking on the edge, waiting to invade our solar system. Not little green creatures, but asteroids from other stars. That’s the conclusion of a new study published in the Monthly Notices of the Royal Astronomical Society.

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Interstellar Comet 2I/Borisov Formed in a Very Cold Environment

Credit: NRAO/AUI/NSF, S. Dagnello

In the summer of 2019, a team of astronomers from NASA, the ESA, and the International Scientific Optical Network (ISON) announced the detection of the comet 2I/Borisov. This comet was the only second interstellar visitor observed passed through our Solar System, coming on the heels of the mysterious ‘Oumuamua. For this reason, astronomers from all over the world watched this comet intently as it made its closest pass to the Sun.

One such group, led by Martin Cordiner and Stefanie Milam of NASA’s Goddard Space Flight Center, observed 2I/Borisov using the ESO’s Atacama Large Millimeter/submillimeter Array (ALMA) in the Chilean Andes. This allowed them to observe the gases 2I/Borisov released as it moved closer to our Sun, thus providing the first-ever chemical composition readings of an interstellar object.

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