The second known visitor to our cosmic neighborhood from another star is making quite an entrance.
No one knows where it came from, but it’s here now. And the chase is on.
Astronomers around the world are monitoring an interstellar comet hurtling through the solar system, known for the moment as C/2019 Q4. It’s the second time in less than two years that they’ve seen an object from another star swing through our cosmic neighborhood. The first time around, the discovery kicked off a worldwide sprint to inspect the object before it got away. It was mysterious enough that some astronomers even began to consider whether it was dispatched by an advanced alien civilization.
This second interstellar object was spotted in late August by Gennady Borisov, an amateur astronomer in Crimea. Borisov has a reputation for catching never-before-seen comets with his telescopes, but they’re from around here; like everything else in the solar system—the planets, the moons, a sea of asteroids—they trace an orbit around the sun. And over the past few weeks, it’s become very clear that this comet does not.