Explanation:
NGC 660 is featured in
this cosmic snapshot,
a sharp composite of broad and narrow band filter image data from
the Gemini North telescope
on Mauna Kea.
Over 20 million light-years away and swimming within
the boundaries of the
constellation Pisces,
NGC 660's peculiar appearance marks it as
a polar ring galaxy.
A rare galaxy type, polar ring galaxies have a substantial population
of stars, gas, and dust
orbiting in rings nearly perpendicular
to the plane of the galactic disk.
The bizarre-looking
configuration could have been caused by the chance capture
of material from a passing galaxy by a disk galaxy, with the captured
debris eventually strung out in a rotating ring.
The violent gravitational interaction would account
for the myriad pinkish star forming regions scattered along NGC 660's ring.
The
polar ring component can also be used
to explore the shape of the galaxy's otherwise unseen
dark matter
halo by calculating the
dark matter's gravitational
influence on the rotation of the ring and disk.
Broader than the disk, NGC 660's ring spans over 50,000 light-years.
