Yep! The problem with looking for "extra-solar" planets (planets around other stars) is that even planets as large and massive as Jupiter are basically invisible to us. It is almost miraculous that (as was recently announced) 100 such planets have been found around relatively nearby stars, essentially in each case by the gravitational or light effect they have on the stars they orbit.

This is the ratio of the volumes, so it would be "crushed up."

Tightly packed spheres occupy about 80 percent of the total volume, so there would be a reduction to about 1,000,000 if you were talking spheres.

Yes! The sun rotates around its axis, an imaginary line right down the center of it, just like Earth. And the Sun, along with the entire solar system, orbits around the Milky Way, our galaxy, at about 200-300 kilometers/sec. Not only that, but the Milky Way moves in space too. You can find some more information on the moving Milky Way at http://starchild.gsfc.nasa.gov/docs/StarChild/questions/question18.html.

The sun's core (the center of the sun) is made up of hydrogen fuel that's converted to helium to produce light and energy. Once this fuel is gone (i.e., the sun used it all up) in about 5 billion years, the core will collapse and produce enough energy to expand the Sun's outer layers, all the way to the Earth's orbit! This makes the Sun a red giant.

The outer layers will keep expanding and the core will keep contracting until all that's left is the core itself (about the size of the Earth now). The helium that's left in the core will eventually fuse (link) into carbon and the core that is left is what we call a white dwarf. The outer layers will glow in a ring given the radiation coming out of the white dwarf, this is called a planetary nebula (it has nothing to do with planets). The white dwarf will eventually cool into invisibility.

The International Astronomical Union (IAU) decides on names for things in the Solar System, such as planets, asteroids, and moons. I asked Dr. Aksnes, the chairman of the group that decides on names for planetary systems and what's in them, this question. It turns out that the IAU has not decided on a single name for the Sun (or the Moon for that matter), but supports the common practice of using the name of the Sun (or the Moon) in any language. Without capitalization, the word "sun" can be interpreted as any other star and the word "moon" as any other moon.