What are black holes?

We can't see black holes. That's because the gravity of these objects is extremely powerful. So powerful in fact, that not even light can escape from it.

Actually, anything that enters a black hole is trapped there and can never escape.

Escape velocity is the term scientists use when they talk about the speed a rocket must travel at to break free from the Earth's gravitational pull and enter outer space. The same term also applies to other objects in space.

Since we know that light can't escape from these objects, their escape velocity is greater than the speed of light.

How do we know where they are?

Scientists can detect these objects in outer space because they can see gas swirling around them at very high speeds. These swirling areas of gas cause hotspots in space. Areas of gas that are hotter than in normal conditions.

How many kinds are there?

There are 3 different kinds of these super-dense objects that we know about:

  • stellar mass: This object has the mass of a star. These objects have anywhere from 3 times the mass of our Sun to as much as 100 times the mass of our Sun. They are about the size of neutron stars. These objects generally form from supernova explosions. They may also form in ways we don’t yet know of.

  • super massive: This object has a mass of hundreds of thousands to over a billion times the mass of our Sun. These objects are usually found at the center of galaxies. Our own galaxy, the Milky Way, has one called "Sagittarius A star". Its mass is over 1 million times the mass of the Sun. our solar system orbits around it about once every 226 million years.

    Some astronomers believe that these super massive objects are at the center of all normal galaxies.

  • intermediate: Scientists aren't exactly sure what these objects are. Some scientists believe they are early stage black holes that will continue gaining mass. They are about 500 to 1000 times the mass of the Sun.

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