Explanation:
The first identified compact galaxy group,
Stephan's Quintet
is featured in
this eye-catching image constructed with data drawn from
the extensive Hubble Legacy Archive.
About 300 million light-years away, only four of these five galaxies
are actually
locked
in a cosmic dance
of repeated close encounters.
The odd man out is easy to spot, though.
The interacting galaxies,
NGC 7319, 7318A, 7318B, and 7317
have an overall yellowish cast.
They also tend to have distorted
loops and tails, grown under the
influence of disruptive gravitational tides.
But the predominantly bluish galaxy, NGC 7320,
is closer, just 40 million light-years distant,
and isn't part of the interacting group.
Stephan's Quintet
lies within the boundaries of the high flying
constellation
Pegasus.
At the estimated distance of the quartet of interacting galaxies,
this field of view spans about 500,000 light-years.
However, moving just beyond this field, above and to the left,
astronomers can identify another galaxy,
NGC 7320C, that is also 300 million
light-years distant.
Of course, including it would bring the
interacting quartet back up to quintet status.
