Radiant balls of plasma held together by gravity, the stars illuminate the night sky and scatter themselves all around the universe that we live in. Even though they just seem like little spheres of light, stars can actually be some pretty big things. From planets that reflect the suns rays such as Mars or Saturn, to different suns of different solar systems light years away from ours, to even other complete galaxies where other life can reside in. The shining of a star is caused by the thermonuclear fusion of hydrogen into helium in the core of the star. The energy level is so high that it causes the star to glow with an immense amount of light. A star begins as a gravitational collapse of usually hydrogen, helium, and some other heavier elements. When the stars core is dense enough it begins to convert hydrogen into helium releasing lots of energy in the process. The stars pressure prevents it from further collapsing on itself. A star may start as a white dwarf but then grow to become a red giant or, if it gets big enough, the star can collapse on itself and create a black whole.
The extreme mystery of space, the black hole really has no answer. Formed by a star that has collapsed on itself, a black hole is an unknown space phenomena that still stumps even the most intelligent of NASA scientists. A black hole can basically be described as pure gravity. This ball of gravity is so dense and dark that even light can not escape it and it even bends the light and space around it making it look like some sort of special effects. This part between the hole and space is called the event horizon. Once an object enters the even horizon there is no way the object can escape. No one knows what is in a black hole since no one has been able to come close enough to it to find out the affects of it. Although we don't know for sure what happens when you slip into a black hole, theories state that it is a wormhole to another dimension. So the real question is, what would happen if you were sucked into a black hole? Well, your feet would feel stronger gravity than your head so you would actually be torn apart. In a process referred to as "spaghettification", your body would be stretched out and turned into a stream of atoms in a black hole. You would experience time dilation where you would speed up and time would slow down. Not really the best way to go.