But many black holes are actually near impossible to detect.
Black holes are whats left after large stars die and their cores collapse.
Astronomers arekeen to studyblack holes because they can tell us a lot about the ways that stars die.
But we can still detect them through the way they interact with other objects thanks to their strong gravity.
Hundreds of small black holes have been detected by the way they interact with other stars.
There are two different approaches to such detection.
The material circles the black hole, heating up by friction as it does so.
First image of a black hole.
Image via Event Horizon Telescope collaboration et al.
40% off TNW Conference!
This impressive achievement promises a new way of finding the previously elusive class of isolated black holes.
EinsteinsGeneral Theory of Relativitypredicted that massive objects will bend light as it travels past them.
The method has already been used to study everything from clusters of galaxies to planets around other stars.
The authors of this new research combined two types of gravitational lensing observations in their search for black holes.
That suggested the object might be a lone black hole, something which had never been seen before.
The problem was that it could also just have been a faint star.
Eventually this let them calculate the mass and distance of the object which caused the lensing effect.
A star that size and that close should be visible to us.
Since we cant see it, they concluded it must be an isolated black hole.
Taking that many observations with an observatory like Hubble isnt easy.
The telescope is very popular and there is a lot of competition for its time.
Luckily, were at the beginning of a revolution in astronomy.
Thats going to be huge for all areas of astronomy.
Ultimately, the galaxys invisible black holes are about to find it much harder to hide.
