M57: The Ring Nebula
Planetary Nebulae are fascinating objects, out of the ordinary from collections of stars, and excellent beginner targets. M57, the Ring Nebula, is an excellent representative of this class of objects,
M57: The Ring Nebula
Planetary Nebulae are fascinating objects, out of the ordinary from collections of stars, and excellent beginner targets. M57, the Ring Nebula, is an excellent representative of this class of objects, showing a distinct, very round ring with a hollow centre. It is harder to find than M27 because it is quite small and may not be visible in your finder. However, it is placed between two close-spaced stars, and should be within reach of a beginner.
Planetary Nebulae are shells of gas ejected by stars in the late stages of their life. When an ordinary mass star (such as our own Sun) expends all its Hydrogen fuel, internal fusion stops. This stops the outward radiation pressure, which causes the gas to begin to collapse under its own gravity. The collapse raises the internal press