On the other hand, some stars are so dense a cupful of material would weigh tons if it could be brought down to Earth. Inside, stars have temperatures measured in millions of degrees. At their surfaces, temperatures up to 55,000 degrees are common. Stars are a long way off, yet all stars visible from Earth, even with telescopes, are within our own Milky Way galaxy. Astronomers now think many stars may be ringed by planets and other small bodies, just as our Sun has its Solar System of planets, moons, comets and asteroids.
Planets reflect starlight, while stars shine with their own light.
There seem to be more galaxies strewn across the Universe than grains of sand on a beach. Astronomers have seen galaxies of many different shapes and sizes. Many galaxies are very, very far away. In fact, some may be at the most distant edge of the Universe. The light arriving from them takes so long to get to Earth that what we see originated very far back in time.