M57: The Ring Nebula
Image Credit:
NASA,
ESA,
Hubble Legacy Archive;
Composition:
Giuseppe Donatiello
Explanation:
Except for the rings
of Saturn,
the Ring
Nebula (M57) is probably the most famous
celestial band.
Its classic appearance is
understood to be due to our own perspective, though.
The recent mapping of the
expanding nebula's
3-D structure, based in part on
this clear Hubble image,indicates that
the nebula is a relatively dense, donut-like ring wrapped
around the middle of a (American)
football-shaped cloud of glowing gas.
The view from planet Earth looks down the long axis of the football,
face-on to the ring.
Of course, in this well-studied example of a
planetary nebula, the glowing material
does not come from planets.
Instead, the gaseous shroud represents outer layers expelled
from the dying,
once
sun-like star, now a tiny pinprick of light
seen at the nebula's center.
Intense ultraviolet light from the hot central star
ionizes atoms in the gas.
The Ring Nebula is about one
light-year
across and 2,000 light-years away.
Source: NASA