M57 is called the Ring Nebula and it's obvious why. Astronomers estimate that the shell of this planetary nebula was blown off about 20,000 years ago.

The different colors of the shell visible in photographs represent different elements. Helium gas emits blue light, oxygen emits green light, and carbon emits red light. The apparently empty region between the shell and the central star is actually filled with gas. This area only appears as a void because it is so hot that the gas emits most of its energy as ultraviolet rays instead of visible light.

M57 is tiny but bright when viewed from the Earth. Because its brightness is spread over a small area, it is best viewed under high magnification. The 14th magnitude central star (a white dwarf) is difficult to identify without a fairly big telescope.

Click here to see if this object is visible in your sky tonight.