M57: The Ring Nebula
Except for the rings of Saturn, the
Ring Nebula (M57) is probably the most famous celestial band.
This
planetary nebula's simple, graceful
appearance is thought to be due to perspective --
our view from planet Earth
looking straight into what is actually a
barrel-shaped cloud of
gas shrugged off by a dying central star.
Astronomers of the Hubble Heritage Project produced
this strikingly sharp image from
Hubble Space Telescope
observations using natural appearing colors to indicate
the temperature of the stellar gas shroud.
Hot blue gas near the energizing central star
gives way to progressively cooler green and yellow
gas at greater distances
with the coolest red gas along the outer boundary.
Dark, elongated structures
can also be seen near the nebula's edge.
The Ring Nebula is about one light-year across and
2,000 light-years away in the northern
constellation Lyra.