Closest known black hole to Earth, sitting 1,600 light-years away, found by astronomers
Astronomers have discovered the closest known black hole to Earth.
The dormant black hole, dubbed Gaia BH1, sits 1,600 light-years away – three times closer than the last black hole to hold the record – in the constellation Ophiuchus. The black hole weighs 10 times the mass of our sun.
A paper published last week in the peer-reviewed Monthly Notices of the Royal Astronomical Society details the discovery of a "Sun-like star orbiting a dark object." The team of researchers initially identified the black hole using the European Space Agency’s Gaia spacecraft, according to a news release from the Harvard-Smithsonian Center for Astrophysics.
The researchers then made 39 additional observations with six different telescopes worldwide over a span of four months. When using a telescope in Hawaii operated by the National Science Foundation's NOIRLab, the team was able to confirm that the central "dark object" was a dormant black hole.
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"Take the Solar System, put a black hole where the Sun is, and the Sun where the Earth is, and you get this system," said Kareem El-Badry, lead author of the paper and an astrophysicist at the Harvard-Smithsonian Center for Astrophysics and the Max Planck Institute for Astronomy, in the news release.
"While there have been many claimed detections of systems like this, almost all these discoveries have subsequently been refuted," El-Badry said. "This is the first unambiguous detection of a Sun-like star in a wide orbit around a stellar-mass black hole in our galaxy."
The researchers don't know how the binary system, in this case consisting of a star orbiting a black hole, formed in the Milky Way – but they noted that the discovery of Gaia BH1 "suggests the existence of a sizable population of dormant black holes in binaries."
Astronomers estimate that there are 100 million black holes in our galaxy, but only a handful have been confirmed to date.
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The Harvard-Smithsonian Center for Astrophysics notes that almost all of the few black holes that have been confirmed are "active." Scientists can tell if a black hole is active or dormant with X-ray radiation. Active black holes shine bright as they pull surrounding material in space. Dormant black holes do not emit high levels of X-ray radiation, which makes them harder to see.
"If a black hole is not actively feeding (i.e., it is dormant) it simply blends in with its surroundings," the Harvard-Smithsonian Center for Astrophysics said.
What is a black hole?
According to NASA, black holes are a result of "a gravitational field so strong that nothing, not even light, can escape." Most black holes form after a large star dies in a supernova explosion. Stellar collisions can form significantly larger black holes.
The sizes of black holes vary significantly. "Stellar mass" black holes usually weigh 10 to 24 times the mass of our sun, while "supermassive" black holes can be millions or billions of times as massive as the sun, NASA says.
But you don't have to worry about a black hole destroying Earth anytime soon. The odds are incredibly small, scientists say.
"Black holes do not go around in space eating stars, moons and planets. Earth will not fall into a black hole because no black hole is close enough to the solar system for Earth to do that," NASA noted in 2018, adding that the sun isn't big enough to become a black hole.
Contributing: The Associated Press
This article originally appeared on USA TODAY: Black hole discovered as the closest known to Earth, astronomers say
