Black holes may be one of the most terrifying things in existence: A region of spacetime where matter is squeezed together so tight, it has a gravitational pull so strong that nothing can escape from it, not even light.
Of the hundreds of millions (perhaps billions) of black holes scientists suspect are floating around in our galaxy, only about 60 have been found. The closest black hole that we know of is around 3,000 light-years away.
But astronomers believe they've spotted a rogue black hole hidden within a fast-moving cosmic cloud tucked away in a corner of the Milky Way. And they think the new discovery could help know where more of them are lurking.
"We found a new way of discovering stray black holes," said Professor Tomoharu Oka, an Astrophysics professor at Keio University and author of the study in a statement.
Their study, published in The Astrophysical Journal Letters, was performed using the ASTE Telescope in Chile and the 45-m Radio Telescope at Nobeyama Radio Observatory. The team observed molecular clouds around the remnant of a supernova explosion called SNR W44, which is about 10,000 light-years away. But inside the cosmic cloud, which is about two light-years in diameter, they found something intriguing: A black hole.
They named the cloud "the Bullet" because it has a speed of over 100 km per second, which is nearly 300 times the speed of sound in space. It was also moving in an unusual way, and wasn't behaving the way they expected.
Most of the Bullet was moving at a speed of about 50 kilometers per second, but the tip was a lot faster. It also appeared to contain tens times the energy it would have received from the W44 supernova. According to Masaya Yamada, a graduate student at Keio University in Japan and leader of the research, this would be impossible under normal conditions.
The team concluded that there were two explanations, both of which involve a strong gravity source, most likely a black hole. With the current data they have, the researchers say both scenarios are equally likely.
- The "explosion model" — The gas shell of the supernova remnant passed by a black hole, creating an explosion. This would accelerate the gas toward us after the gas shell has passed the black hole.
- The "shooting model" — A high speed black hole stormed through the gas and dragged it along by the strong gravity of the black hole to form a gas stream.
Why are black holes so hard to find?
Black holes are often created when a lot of matter is compressed into a small space, which can happen when stars are dying and collapse in on themselves. This means the gravitational pull is so strong, light cannot escape. When no light can get out, that means there's nothing to see, which is why black holes are invisible.
You would be able to tell if a black hole was nearby, because when they are close enough, you would see the background getting distorted. However, by that point it's already too late for you.
It sounds scary, but we have luck on our side. According to NASA, no black hole is close enough to our solar system for Earth to fall into a black hole, and in 4.5 billion years of our existence we've never encountered one.
So we probably won't meet a black hole for billions or trillions of years, if ever. Even if a black hole the size of the Sun sucked up our light source, it would have the same gravitational pull, and thus Earth and the other planets would just orbit it like they orbit the Sun now. So relax.