Black hole is the region of space which has an extremely intense gravitational field- so intense that no radiation or matter can escape from it. Not even the particles of light can escape from inside it. The gravity is strong owing to the matter that has been squeezed into a tiny space. Since no light can get out, black holes are invisible to the naked eye. There are only space telescopes with certain special tools that can detect black holes. “Black Hole” was coined by John Wheeler in 1967.
HOW BIG IS A BLACK HOLE?
Black holes can be small or big. The smallest of black holes can be as small as an atom but they have the mass which is the size of a mountain. Stellar is a black hole which can be more than 20 times the mass of the sun. Supermassive are the largest of black holes. Every galaxy contains supermassive black hole at its centre like Sagittarius A is the one placed at the center of the Milky Way.
HOW DO THE BLACK HOLES FORM?
They were formed at the very beginning of the universe. Stellar black holes get formed when the center of a huge star collapses and causes a supernova. (Supernova is an exploding star that blasts into parts of stars into space.)
The scientists can see the black hole by studying the stars around it and by studying the strong gravity that affects the stars and the gases around the black hole. A high energy light is formed whenever a star is close to a black hole. This light, though invisible to human eyes, is visible to the satellites and telescopes in space.
CAN A BLACK HOLE DESTROY EARTH?
No. Black holes are not monsters that go around eating up planets, stars and moons in the universe. And Earth cannot fall into the black hole since no black hole is close enough to the solar system so that Earth falls into it. A black hole the size of the sun when placed in the place of the sun even would not be able to destroy Earth owing to the fact that then, the black hole would have the same gravity as the sun and the other planets along with Earth would orbit around it as they do it for the sun. The sun cannot fall into a black hole since the sun isn’t a big enough star for making a black hole.