Explanation:
Big, beautiful spiral galaxy M101 is one of the last
entries in Charles
Messier's famous catalog, but
definitely not
one of the least.
About 170,000 light-years across, this galaxy is enormous, almost
twice the size of our own Milky Way galaxy.
M101 was also one of the original
spiral nebulae
observed by Lord Rosse's large 19th century telescope, the
Leviathan
of Parsontown.
Assembled from 51 exposures
recorded by the Hubble Space Telescope in the 20th and 21st
centuries, with additional data from ground based telescopes,
this mosaic of M101
is touted as the largest, most
detailed
spiral galaxy view ever released from Hubble.
The sharp image shows
stunning features along the galaxy's
face-on disk of stars and dust along with background galaxies,
some visible right through M101 itself.
Also known as the
Pinwheel Galaxy,
M101 lies within
the boundaries of the northern constellation
Ursa Major,
about 25 million light-years away.
