The Jellyfish Nebula in
Gemini is thought to be the
remnant of a supernova that
occurred about 30 thousand
years ago. It is approximately
5000 lightyears distant.
Contrast the appearance with
that of the
Crab Nebula and
Veil Nebula, two other SNR's
(supernova remnant.) To my
eye, interestingly enough, the
Jellyfish resembles the
Crescent Nebula, which is
not a SNR, but rather a
planetary nebula -- one of the
more sedate ways that a star
can end its productive life. In
either case, the red glow
stems from the emission of
light at precisely 656.3 nm,
the so-called hydrogen alpha
emission.
Takahashi FSQ106
SBIG STL11K
Astrodon Series I
RGB filters plus
6nm Ha

Ha(HaR)GB:

Ha = 20 min x 25
R  =  10 min x 15
G  =  10 min x  8
B  =  10 min x 8

The data was processed
with CCDsoft, Registar, Neat
Image, and Adobe PS.
       The Jellyfish Nebula, IC 443
         Click on image to enlarge