The comet was first spotted by Gennady Borisov, an astronomer at the MARGO observatory in Nauchnij, Crimea. Word of Borisov’s discovery quickly spread among astronomers.
The Scout system, a comet and asteroid-tracking program based out of NASA’s Jet Propulsion Laboratory, determined C/2019 Q4 didn’t have an elliptical orbit and flagged it as a possible interstellar visitor.
Astronomers have scrambled to gather additional observations and more precisely work out the comet’s trajectory and origins.
“The comet’s current velocity is high, about 93,000 miles per hour, which is well above the typical velocities of objects orbiting the Sun at that distance,” Davide Farnocchia, researcher at NASA’s Center for Near-Earth Object Studies, said in a news release. “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.”
Currently, the comet — which appears only as a moving speck in images — is located 260 million miles from the sun. It will reach its closest approach to the sun at 190 million miles.
As Quanzhi Ye, an astronomer at the University of Maryland, explained to National Geographic, the comet boasts an unusually high orbital eccentricity. The more circular a comet’s orbit is, the closer its eccentricity is to zero. Comets with very stretched-out, oblong orbits boast eccentricities closer to one. C/2019 Q4’s eccentricity is three.
What’s more, the comet’s trajectory is 44 degrees off-kilter from the orbital plane of the solar system’s planets.
“That’s why we say that gravitational perturbations are almost impossible,” Ye said.
In other words, the comet’s odd trajectory isn’t a glitch or brief anomaly. It’s path through the solar system suggests it is an interstellar visitor.
C/2019 Q4 has yet to be official confirmed as a visitor from outside the solar system, but if and when it is, it will be just the second one — after ‘Oumuamua — to be spotted by astronomers. Scientists estimate hundreds of thousands of interstellar visitors are passing through the solar system at any given moment, but most of them are too small and too far away to ever be spotted by telescopes.
Despite limited observations, Karen Meech and a team of astronomers at the University of Hawaii determined that the comet’s nucleus measures between 1.2 and 10 miles in diameter.
As the comet continues on its path through the solar system, astronomers will continue to observe it. As it gets closer, scientists hope to more precisely calculate its trajectory, as well as work out its size, shape and composition.