Discover the cosmos! Each day a different image or photograph of
our fascinating universe is featured, along with a brief
explanation written by a professional astronomer. January 25,
1997 Explanation: The Whirlpool Galaxy is a classic spiral
galaxy. At only 15 million light years distant, M51, also
cataloged as NGC 5194, is one of the brighter and more
picturesque galaxies on the sky. The smaller galaxy appearing
here above and to the right is also well behind M51, as can be
inferred by the dust in M51's spiral arm blocking light from
this smaller galaxy. Astronomers speculate that M51's spiral
structure is primarily due to it's gravitational interaction
with this smaller Authors & editors: NASA Technical Rep.: Jay
Norris. Specific rights apply. A service of: LHEA at NASA/ GSFC
&: Michigan Tech. U.