The closest black hole to Earth may have been spotted 1,000 light-years away
The closest black hole to the solar system ever spotted may be just 1,000 light-years away. This newfound dark neighbor is at least 4.2 times as massive as the sun, and lives with two ordinary stars whose funny orbits gave the black hole’s presence away, astronomers report May 6 in Astronomy & Astrophysics. Astronomers expect the Milky Way to harbor between 100 million and a billion black holes with masses between a few and 100 times the sun’s. But most of those black hole are invisible. “If it’s lonely out there without a companion, you’ll never find it,” says astrophysicist Thomas Rivinius of the European Southern Observatory in Santiago, Chile. The few dozen small black holes that have been spotted so far interact violently with their environments, gobbling up gas from a companion star and heating the gas until it emits X-rays (SN: 4/4/18). The previous nearest known black hole, called V616 Mon, emits X-rays from about 3,200 light-years away. The new neighbor black hole, called HR 6819, is...