Scientists measure the visible light, X-rays, and radio waves emitted by the objects around a black hole. When a normal star orbits around a black hole, they can measure the speed of the star by studying the light it gives off. This also tells them the mass of the black star.
In 1915, the theory of general relativity, by Einstein, predicted the existence of black holes. And in 1967, American theoretical physicist, John Wheeler, applied the term ”black hole" to these collapsed objects.
Black holes may solve some of the mysteries of the universe.
How do scientists know black holes are there?
They see how the back hole’s gravity affects the stars and has around them and if stars are orbiting them. Also, if a star and black hole are close, high energy light is created.
Could a black hole destroy Earth?
Although black holes do suck in everything near them, they don’t go around eating stars, moons and planets. Even if the sun turned into a black hole, the Earth would not be pulled in because it would have the same gravitational pull on Earth. And even then, the sun couldn’t turn into a black hole because it’s too small.
Facts about black holes: