Explanation:
At first glance, the Helix Nebula
(aka
NGC 7293), looks simple and round.
But this well-studied example of a
planetary nebula, produced
near the end of the life of a sun-like star, is
now understood to have a surprisingly
complex geometry.
Its extended loops and comet-shaped features have been
explored in Hubble
Space Telescope images.
Still, a 16-inch diameter telescope and camera with broad and
narrow band
filters was used to create
this sharp view of the Helix.
The color composite also reveals the nebula's intriguing details,
including light-year long, bluegreen radial stripes or spokes that
give it the appearance of a cosmic bicycle wheel.
The spoke features seem to indicate that the Helix Nebula
is itself an old and
evolved
planetary nebula.
The Helix is a mere seven hundred light years from Earth,
in the constellation
Aquarius.
digg_url = 'http://apod.nasa.gov/apod/ap080904.html'; digg_skin = 'compact';
