Burnt Out Stars
There are also some very peculiar objects out there.
White dwarfs are the hot cores of stars that have blown away their outer layers. They are about the same size as the Earth.
Neutron stars are the cores of stars that have been compressed to a very small size by gravity and are cooling off slowly. They are barely as large as a small town.
Black holes are the stangest object in space. They are the core of stars that gravity has compressed down so small that nothing can escape not even light. They are even smaller than neutron stars.
These former stars have densities ranging from a million to a trillion times the density of the sun and more. Just to give you some idea of how incredible this really is let's look at the difference in density between air and solid rock. Let's pick gold for example. Gold is 16 thousand times more dense than air. So the change in density between the sun and a white dwarf or neutron star is more than the difference between air and rock!
The Why of It
The burning question is why? Why are stars born in such a wide variety of sizes and colors? Are there limits on how large or how small a star can be? How do normal stars change into black holes and neutron stars? And how do we know what we know?