Diane has taught all subjects at the elementary level, was the principal of a K-8 private school and has a master's degree in Measurement and Evaluation.
What Is a Black Hole?
You probably already know that gravity is the reason that things fall and break, like your mom's favorite vase when you accidentally hit it with your soccer ball. But the Earth isn't the only place in the universe where you'll find gravity.
Gravity is a force that attracts two objects to each other. Black holes are areas in space where the force of gravity is so strong that not even light can escape its pull, like a game of tug-of-war you can't win.
You know that the moon and stars exist because they reflect light and you can see them. But scientists can't actually see black holes since they pull light in but don't let it out. They know they are there, however, by the way gases and stars move and act when they are near a black hole.
How do Stellar Black Holes Form?
Stellar black holes are smaller black holes that form when huge stars with about ten to twenty-four times as much matter as our Sun die. The dying star caves in on itself like a building when it's demolished, creating a giant supernova, which is a star that explodes. That enormous explosion sends the outer bits of the star into space. All that is left is the collapsing center. If the center has enough matter, the strong gravity in the center squeezes it so much as it collapses that it turns into a black hole. Scientists think there may be as many as a billion of these black holes in our galaxy, the Milky Way!
Neutron Star Crash
Stellar black holes are also created when two neutron stars, which are small, dense stars made of the core of dead stars, crash into each other, like bumper cars in space. The collision sends out a giant burst of radiation called a gamma-ray, as a new stellar black hole is formed.
How do Supermassive Black Holes Form?
Supermassive black holes are enormous and have millions or maybe billions of times as much matter as the Sun. Scientists think that there is a supermassive black hole in the middle of all big galaxies. The Milky Way where we live has one called Sagittarius A (pronounced saj-ih-TARE-ee-us A).
Scientists aren't exactly sure how these huge black holes form, but they have some different ideas:
- Some think huge gas clouds caved in on themselves when galaxies were first forming.
- Others think these black holes start out as stellar black holes that grow over millions of years because they suck in so much material, like a giant tub drain.
- Still other scientists think that a group of stellar black holes combine to form one supermassive black hole.
There are different kinds of black holes, which are areas in space where there is a lot of matter squeezed by the force of gravity, which is so strong that even light can't escape its pull.
Stellar black holes are smaller and form:
- When a huge star dies and explodes, and then the matter in the core is squeezed by strong gravity
- When two neutron stars crash into each other and form a new stellar black hole
The much bigger supermassive black holes may form:
- When huge gas clouds cave in on themselves
- When stellar black holes suck in a lot of material over millions of years
- When stellar black holes combine to form one supermassive black hole
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