The Ring Nebula (M 57) in the constellation Lyra is the glowing remains of a dying star. About 4000
years ago, a star several times larger than our sun began to use up the fuel in its core.
The star expanded as it became a "red giant," and it expelled its outer layers into space.
As the star's inner furnace finally failed, the star collapsed into an extremely hot and dense
"white dwarf," whose ultraviolet radiation now causes the previously expelled gasses to glow.

The Ring Nebula is a donut of expanding gas that we see looking through the "hole."
The middle of this donut, however, has a filling: the center of the donut is filled with an
oblong shell of helium (blue) and oxygen (green) cast out by the dying star.
The outer, red halo around the "ring" itself is hydrogen.

In roughly 5 billion years, our own sun will meet a similar fate as it uses up its fuel. Our sun
is several times smaller than the star that produced the Ring Nebula, so perhaps it will not
result in such a stunning sight. However, it will engage in the same process of recycling that is
happening in the Ring Nebula, as elements forged in the heat and pressure of a star are sent out
into the galaxy to be formed, eventually,into new stars and planets.

The Ring Nebula is about 2000 light years from earth, and about 1 light year across.
The small spiral galaxy above and to the right (IC 1296) is, by contrast,
a staggering 221 million light years away, no doubt containing uncounted nebulae of its own.

Image Data:
Camera: SBIG STL-11000
Telescope: Hyperion 12.5"
Exposure: 18 1/4 hours total
(Luminance: 5 1/4 hours; Hydrogen-alpha: 6 hours; RGB: 7 hours)