What is a Black Hole?
Created | Updated Jan 28, 2002
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What is a Black Hole?
When a star starts to run out of fuel the atoms are less hot and they starts moving around less. This means that the star has a stronger grip of gravity on its self and so it pulls its self together harder and get smaller and denser and the gravity there for gets stronger and so on. In the end a star more than two and a half time as massive as the sun explodes in a supernova explosion leaving just to core. The core contracts as dense as it can until it leaves just a neutron star that had all the atoms in it a dense as they can. However if the star is large enough then it overrides the exclusion principle that states that two atoms cannot occupy the same space and the star continues collapsing.
On a neutron star the gravity is enormous. One pinhead of matter from a neutron star would weight as much as two of world’s heaviest super tankers. A 9 pound (4 kilogram) baby would weight 90,000 million pounds (40,000 million kilograms) on the surface of a neutron star. In a Black Hole the gravity gets so great that the escape velocity of it exceeds 186,000 miles per second (300,000 kilometres per second). This is the speed of light and since this is the speed limit of the Universe nothing can escape from the black hole. Light, matter, time, nothing. This means that since no light can escape from the black hole we can’t see it. All we can see is darkness and that is why it is said to be black. It could be green but we can only see darkness and the colour of darkness is black.
The black hole is surrounded by two event horizons. An outer event horizon and an inner one. The outer event horizon is where the black hole starts. Once something passes the event horizon it cannot escape and will pass the inner event horizon. It is believed that past the inner event horizon you can move around as you could in normal space but not out. In the end you will hit in singularity as the centre and be crushed. When approaching the Black hole part of you that is nearer the Black Hole will be pulled towards the Black Hole faster than the part of you that is further away and you get stretched and we call this spaghettification.
There is another way that a Black Hole is made. At centre of a galaxy all the stars are closer together than others that are further out and the gravity of one star could deflect the path of another star. In the end some stars could be heading for the centre of the galaxy where they fuse together. Their gravity becomes greater and they pull more stars in and in the end the gravity is so great that they become a super massive Black Hole. It is thought that most galaxies have a super massive Black Hole at the centre. It is believed that there is one in the centre of the Milky Way, weighing in at the weight of 4 million suns, called Greedy Guts that destroy the equivalent of 3.3 Earths a year.
I have made several batches of questions. This question is from the first batch. To find other batches of questions plus the newest one return to the main h2g2 as Q and A page using the first link below. Other questions in this batch are also below.
| h2g2as Q and A | Find the answers to many space related questions. |
| How old is the Universe? | The age of the Universe and how we managed to work it out. |
| How did the Universe begin? | The origins of the Universe, how we found then out, proved them and The Big Bang. |
| How will the Universe end? | Three throrys about the death of the Universe and how to decide which will be the one. |
| What was it like before the Big Bang? | BEFORE the Big Bang. One of the most asked questions asked by anyone who knows anything about the Big Bang. |
| What is a Black Hole? | About the most bizzare objects in the Universe and how they are created. |
| What is a Wormhole? | How to travel anywhere in the Universe in seconds. |
| What is a quasar? | About the brightest objects in existance but which are also the most distant. |
| What happens at the speed of light? | What will happen when you catch up with light. CAN you catch a light beam? |
| Is there any life out there? | Are we alone? The search for ET. |
| What is space made out of? | The story of nothing. |
| What is ‘Dark Matter’? | The hunt for the missing matter of the Universe. |
| Where is the centre of the Universe and where is the edge of the Universe? | "Here is where the Universe began. Visit the Big Bang cafe and souvenir shop." |
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Richard Derek Young.
