NGC 660 lies near the center of this field of
galaxies within the boundaries of the constellation Pisces. Over
20 million light-years away, its 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 a flat galactic
disk. The bizarre configuration could have been caused by the
chance capture of material from a passing galaxy by the disk
galaxy, with the captured debris strung out in a rotating ring.
Polar Ring galaxies can 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 about
40,000 light-years.
