The closest black hole to Earth's solar system has been discovered by a team of astronomers who say it was hiding in plain sight only about 1,011 light-years away.
The black hole -- which NASA defines as a great amount of matter packed into a very small area with a gravitational field so strong that nothing, not even light, can escape -- was discovered in a star system called HR 6819 and is about four times the mass of the sun, according to the findings published on Wednesday in the scientific journal Astronomy & Astrophysics.
"We were totally surprised when we realized that this is the first stellar system with a black hole that can be seen with the unaided eye," Petr Hadrava, co-author of the study and emeritus scientist at the Academy of Sciences of the Czech Republic in Prague, said in a statement.
Scientists stumbled upon the out-of-this-world discovery in the Telescopium constellation while tracking two stars orbiting each other just outside the gravitational pull of the black hole, with the help of a super telescope at the European Southern Observatory's La Silla Observatory in Chile.
The HR 6819 black hole is similar in size to ones found in the Milky Way, which is about 25 million light-years from Earth's solar system in the constellation Canes Venatici, according to researchers. Based on the cosmic distance scale, one light-year equals about 6 trillion miles.
"Usually when you have a black hole with a star around it, we can't actually see the star go around the black hole," study co-author Marianne Heida, a postdoctoral fellow at the European Southern Observatory, told National Geographic. "This one is so close by, we should be able to to see the motion ... and that means you could get a much better handle on the black hole's mass, if it all works out."
Other stargazers were buzzing about the major discovery that could give astronomers their best chance at unlocking the mysteries of the galactic phenomenon.
"It seems like it's been hiding in plain sight," astronomer Kareem El-Badry, a Ph.D. student at the University of California, Berkeley, who wasn't involved with the study, told National Geographic. "It's a bright enough star [system] that people have been studying it since the 80s, but it seems like it's had some surprises."
While most black holes are invisible, scientist managed to capture the first image of one last year. The never-before-seen black hole is in a galaxy far, far away called Messier 87. Located near the center of that galaxy, it's about 53 million light-years from Earth.
The image was captured by the Event Horizon Telescope, a network of observatories spanning the globe.