World / Science & Health

Scientists say newly discovered comet is likely to be an 'interstellar visitor'

Reuters

A newly discovered comet hurtling toward the orbit of Mars has scientists scurrying to confirm whether it came from outside the solar system, a likely prospect that would make it the second such interstellar object observed in our planetary neighborhood.

The trajectory of the comet, first detected by Crimean astronomer Gennady Borisov, follows a highly curved path barreling in the sun’s direction at unusually high speeds, evidence that it originated beyond the solar system.

“On our team we’ve been scrambling here at the University of Hawaii to get observations to make position measurements,” said Karen Meech, an astronomer at the university whose team concluded that the object’s size and tail of gas classify it as a comet.

“Every time a new comet is discovered, everybody starts to try and get data so that you can get the orbit,” Meech said, adding that her researchers “all are 100 percent convinced that this really, truly is interstellar.”

The comet, an apparent amalgam of ice and dust, is currently 420 million kilometers (260 million miles) from the sun and is expected to make its closest approach on Dec. 8, putting it 300 million kilometers (190 million miles) from Earth, on a route believed unique to such objects of interstellar origin.

Once confirmed as interstellar, the comet — dubbed C/2019 Q4 by astronomers — would become only the second such body ever observed by scientists.

The first was a cigar-shaped comet dubbed ‘Oumuamua — a name of Hawaiian origin meaning a messenger from afar arriving first — that sailed into our planetary neighborhood in 2017, prompting initial speculation that it may have been an alien spacecraft. Astronomers soon reached a consensus that it was not.

Unlike ‘Oumuamua, which visited the solar system for only a week, the newfound comet will linger near Mars’ orbit for almost a year, giving scientists ample time to characterize its chemical signatures and seek further clues about its origin.

“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,” said Davide Farnocchia, an astronomer at NASA’s Jet Propulsion Laboratory in California who worked with astronomers in the United States and Europe to estimate the comet’s trajectory and determine whether it originated within our solar system. On Oct. 26, the comet will pass through the plane in which Earth and the other planets orbit the sun from above, relative to Earth, at a 40-degree angle.

The comet’s fuzzy appearance indicates that it has a central icy body that is producing a surrounding cloud of dust and particles as it approaches the sun and heats up, according to NASA.

NASA said that observations by Meech and her team indicate the comet nucleus is somewhere between 1.2 and 10 miles (2 and 16 kilometers) in diameter. Future observations will further determine its size and rotation and better identify its trajectory.

Its location in the sky as viewed from Earth places it near the sun, where ground-based asteroid surveys and asteroid-hunting spacecraft usually don’t search.

C/2019 Q4 is now very dim, around magnitude 18, but professional telescopes will be able to track it for months to come. NASA said it will be observable with moderate-size professional telescopes until April.

Information from NASA added