1. Black Holes

2. Myth or Reality?
Black holes are giant, cosmic vacuum cleaners that swallow up everything around them.

3. Myth
Reality: Black holes do not suck up nearby material. If the Sun were magically converted into a black hole, Earth's orbit would not change. Material generally falls into a black hole when it collides with other material orbiting the black hole. The collision alters the material's orbit. Instead of orbiting a comfortable distance from the black hole, the material is now orbiting too close to the black hole. Then the black hole's enormous gravity traps the material in a one-way spiral to oblivion.

4. Myth or Reality? You can see a black hole.
Myth or Reality?

5. Myth
The light produced or reflected by objects makes them visible. Since no light can escape from a black hole, we can't see it. Instead, we observe black holes indirectly by their effects on material around them.

6. Black holes lead to other places.
Myth or Reality?
Black holes lead to other places.

7. Myth
In science fiction shows, people sometimes travel through wormholes. Many students think black holes are wormholes and therefore lead to other places. Wormholes don't exist; they are merely a hypothesis.

8. Dark Matter About 90% of galaxies consist of dark matter.
Black holes are a type of dark matter.

9. Micro Black Holes These black holes are hypothetical.
Their mass would be less than a star.
The smallest possible black hole.

10. Stellar Mass Black Holes
These black holes are formed by the gravity from the death of a massive star.
The star has a supernova explosion when it dies and the corpse becomes a black hole.

11. Intermediate Black Holes
These black holes have significantly larger mass than stellar mass black holes.
And are significantly smaller than supermassive black holes.

12. Supermassive Black Holes
These are the most massive black holes.
Scientist have evidence that there is a supermassive black hole in the center of each galaxy including the Milky Way.

13. How they are formed
When a giant star dies, all of its mass is squeezed in a single point.
Time and space stop
Mass has no volume and time does not pass

14. Parts of a black hole
The center of a black hole is called the singularity.
Within a certain distance from the black hole is the event horizon. This is where the gravitational force is so strong, anything that passes will be sucked in, including light.

15. Parts of a black hole continued...
The more massive the singularity, the larger the event horizon.
The event horizon is the point where nothing can go back.
Nothing gets sucked into the event horizon, it has to pass through it to become caught in it.

16. Gravitational Force
Albert Einstein was the first to discover gravity in 1916.
Gravitational waves are created when two big masses spin, collide or explode.

17. Gravitational force of a black hole
The gravitational force of a black hole is the same as when it was a star.
Our sun is an average size star, if it were to die and become a black hole the Earth's orbit would not change because the gravitational force would not change. This is why objects such as planets are safe from black holes.

18. Spaghettification in Black Holes
When the gravitational force is so strong it stretches objects into long, thin shapes like spaghetti.
No object can resist this strong gravitational force near black holes.
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19. Finding a black hole
Although black holes are black, when matter falls into them, it can heat up so much that it glows in x-rays.

20. In the Milky Way Galaxy
Scientist have evidence that they have found a black hole in the center of our galaxy.

21. In the Milky Way Galaxy
The evidence for this is a star near the center of our galaxy is spinning at speeds of up to 3000 miles per second. That is REALLY fast!
Only a black hole 3 million times the size of our sun could cause a star to move so fast

22. Questions about black holes
If you want to know more about black holes, ask your parents to look at these web sites
s/ask_astro/black_holes.html