NASA Says a New Comet is Likely an Interstellar Object From Another Star System

Astronomers think object C/2019 Q4 (the green line) could be an interstellar object, perhaps a comet from another star system.

Astronomers may have spotted the second object ever to visit our solar system from another star system. The object may even fly near Mars in October.

Right now, the chances are much higher that the object, known as comet “C/2019 Q4 (Borisov)” (or “gb00234”), is interstellar, rather than a rock from within the solar system. But scientists are not yet entirely certain.

The first such interstellar object ever detected, the mysterious and cigar-shaped ‘Oumuamua (which a few scientists controversially argued may be alien in origin), zoomed through our solar system in 2017.

An amateur astronomer in Crimea, Gennady Borisov, first spotted C/2019 Q4 in the sky on August 30. It hasn’t yet entered our solar system, but astronomers have been collecting data in hopes of plotting the object’s path through space and figuring out where it came from.

“It’s so exciting, we’re basically looking away from all of our other projects right now,” Olivier Hainaut, an astronomer with the European Southern Observatory, told Business Insider. Hainaut was part of a global team of astronomers that studied ‘Oumuamua as it passed through the solar system two years ago.

“The main difference from ‘Oumuamua and this one is that we got it a long, long time in advance, ” he added. “Now astronomers are much more prepared.”

Why this newly discovered comet is likely from another star system

A telescope system at NASA’s Jet Propulsion Laboratory, called Scout, automatically flagged C/2019 Q4 as a potential interstellar object. Though the comet’s origin has not yet been confirmed, it’s traveling at 93,000 miles per hour and is expected to cross our solar system’s orbital plane on October 26.

“The high velocity indicates not only that the object likely originated from outside our solar system, but also that it will leave and head back to interstellar space,” Davide Farnocchia, who studies near-Earth objects at NASA, said in a press release.

The object’s core is between 1.2 and 10 miles (2 and 16 kilometers) in diameter. It’s expected to pass through our solar system outside Mars’ orbit and get no closer to Earth than 190 million miles (300 million kilometers).

Early images suggest C/2019 Q4 is followed by a small tail or halo of dust. That’s a distinct trait of comets — they hold ice that gets heated up by nearby stars, leading them to shoot out gas and grit into space. The dust could make C/2019 Q4 simpler to track than ‘Oumuamua, since dust brightly reflects sunlight.

That reflected light could also make it easier for scientists to study the object’s composition, since telescope instruments can “taste” light to look for chemical signatures.

“Here we have something that was born around another star and traveling toward us,” Hainaut said. “It’s the next best thing to sending a probe to a different solar system.”

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Source: Business Insider