What is a black hole?
A black hole is the result of a star that is at least 25 times the mass of the Sun, dying. When these giant stars die, they blow up in a powerful explosion called a supernova. A supernova’s explosion makes a star’s outer layers to shoot out into space. As this happens, the star’s heavy core pulls the rest of the star inward, which causes the star to collapse. The collapse is caused by the core’s extreme gravity, and, as these enormous stars contain a lot of mass, their gravitational pull is extreme. After a supernova, a star’s core is so compact, and its gravity is so strong that the core gets crushed into a miniscule point. Thus, the star becomes a black hole.
Spaghettification
Do you ever wonder what would happen if you were to somehow fall into a black hole? If you have passed the event horizon – the reason black holes don’t just swallow everything up – you get sucked into the singularity. The singularity is the centre of the black hole which is so small that it can’t be seen even with a microscope. Still, no one knows what the singularity of a black hole looks like as nothing can go into a black hole and survive. As you are being drawn in, you become spaghettified. Although the name seems fun – don’t be fooled. When you come near to the black hole, you start to get pulled apart by its gravitational pull. By the time you reach the core of the black hole, you would only be a thin sliver of matter or like a long strand of spaghetti, hence why scientists sometimes call this process ‘spaghettification.’
Different Kinds of Black Holes
Black holes come in all sorts of sizes, from mini to supermassive. A mini black hole can be even smaller than a star and can have the same mass as a comet. However, they are still too small to see with human eyes. Some scientists think that trillions of micro black holes appeared when the universe was born roughly 14 billion years ago, as, long ago, all the matter in the entirety of the universe was packed into a tiny space. Some areas of space were so compacted that they became mini black holes. Some scientists believe that the majority of these have disappeared, although a few may still exist.
Stellar-mass black holes are black holes formed from supernovas. The largest stars in the universe are the only ones that can become stellar-mass black holes. As previously mentioned, our Sun is medium-sized and therefore is too small to become a black hole of this type when it dies. To create a stellar-mass black hole, scientists think that a star must have a mass of at least 10-15 times the size of our Sun.
Intermediate-mass black holes are black holes that have a mass between stellar-mass and supermassive black holes. Sometimes intermediate-mass black holes can also be referred to as “middle-weight” black holes. Scientists aren’t actually sure where these middle-weight black holes come from however some posit these are simply just supermassive black holes that never finished growing.
The final type of black holes are the supermassive black holes, these are enormous black holes that are millions of times larger than the Sun. Scientists are also unsure how these giants were created, but one idea is that many smaller black holes merge together until they form a single supermassive black hole. Many galaxies have a supermassive black hole at the centre of them.
Sagittarius A* is the name of the supermassive black hole inside of our Galaxy, the Milky Way. The mass of Sagittarius A* is equal to approximately 4 million of our Suns, but since Sagittarius A* is roughly 26,000 light years (9,460,700,000,000 Kilometres) away, we here on Earth have nothing to worry about.
Some final Fun Facts to leave you with.
- Once black holes were called invisible stars.
- A supernova emits as much energy in the time it takes to explode as our Sun does in billions of years.
- The most powerful black holes can be found in the centres of galaxies.
- Scientists think that the Milky Way galaxy could contain millions of stellar-mass black holes.
- The smallest known black hole has a mass of 4 Suns.
Resources
Bibliography
Than, Ker. Black Holes (A True Book: Space). New York: Scholastic, 2010.
DeCristofano, Carolyn Cinami. A Black Hole Is Not a Hole. Massachusetts: Charlesbridge, 2012.
