Explanation:
Is this one galaxy or two?
The jumble of stars, gas, and
dust that is NGC 520 is now thought
to incorporate the remains of two separate galaxies.
A combination of observations and simulations indicate the
NGC 520
is actually the collision of two disk galaxies.
Interesting features of NGC 520 include an unfamiliar looking
tail of stars at the image bottom
and a perhaps more familiar looking
band of dust
running diagonally across the image center.
A similar looking collision might be expected were our disk
Milky Way Galaxy to
collide with our large galactic neighbor
Andromeda (M31).
The collision that defines
NGC 520
started about 300 million years ago and continues today.
Although the speeds of stars are fast, the distances are so vast that the interacting pair will surely not change its shape noticeably during our lifetimes.
NGC 520, at visual
magnitude 12,
has been noted to be one of the brightest interacting galaxies on the sky,
after interacting pairs of galaxies known as the
Antennae.
NGC 520 was
imaged above in spectacular fashion by the
Gemini Observatory in
Hawaii,
USA.
Also known as
Arp 157,
NGC 520 lies about 100 million
light years
distant, spans about 100 thousand light years, and can be seen with a
small telescope toward the
constellation of the Fish
(Pisces).
