Black Holes

About Black Holes

• A black hole is a place in space where gravity pulls so much that even light cannot get out. The gravity is so strong because matter has been squeezed into a tiny space.

• This can happen when a star is dying (our sun will never turn into a black hole as it is not big enough to make a black hole)

• Because no light can get out, people can't see black holes. They are invisible.

• Black holes do not go around in space eating stars, moons, and planets. Earth will not fall into a black hole because no black hole is close enough to the solar system for Earth to do that.

Detection of Black Holes:

1.They cannot be directly observed because they themselves do not emit or radiate light, or any other electromagnetic waves that can be detected by instruments built by human beings.

2.But the area just outside the boundary of the black hole (Event Horizon), which has vast amounts of gas, clouds and plasma swirling violently, emit all kinds of radiations, including even visible light.

• Space telescopes with special tools can help find black holes. The special tools can see how stars that are very close to black holes act differently than other stars.

3.Hence, the presence of black holes can be inferred by detecting their effect on other matter nearby them.

Importance of studying Black Holes

Tiny Black Holes

• As small as just one atom.

• These black holes are very tiny but hove the mass of a large mountain.

• These block holes were formed when the universe began.

Stellar Black Holes

• Its mass can be up to 20 times more than the mass of the sun.

• There may be many, many stellar mass block hole in Earth's galaxy (the Milky Way)

• They were formed when the center of a very big star falls in upon itself, or calliopes

• When this happens, it causes supernova (supernova is an exploding star that blasts part of the star into space)

Supermassive black holes

• These block holes have masses that are more than 1 million suns together.

• Supermassive black holes were made at the same time as the galaxy they are in.

Basic Parts of Black Hole

Singularity: It is the one-dimensional point in the center of a black hole which contains a huge mass in an infinitely small space, where density and gravity become infinite and space-time curves infinitely. It is a tiny volume with very big density.

The event horizon: It is the "point of no return" around the black hole. It is not a physical surface, but a sphere surrounding the black hole that marks where the escape velocity is equal to the speed of light.

The Schwarzschild Radius: This is the event horizon's radius. It is the radius at which the escape velocity is equal to the speed of light.

The Ergo sphere: If the black hole is rotating, then as it spins, its mass causes the space time around the black hole to rotate as well. This region is called the ergo sphere

The Accretion Disk: This is a disk composed of stellar material that is spiraling towards that black hole.