For a long time, people believed that everything in the sky was
perfect and ordered, but we now know that things are just as chaotic up
there as they are down here.
A newly released Hubble picture
shows just how beautiful a mess this can be. The image shows UGC 4459,
an irregular dwarf galaxy located 11 million light-years from the Milky
Way in the constellation of Ursa Major (The Great Bear).
UGC 4459's stellar population is spread out (diffused) and
disorganized, with clumps of young blue stars, red old stars, and
extended clouds of gas shining in red. It is composed of several billion
stars, and although that might seem like a lot, it's tiny compared to
galaxies such as the Milky Way, which has a mass of 100 billion suns.
Irregular dwarf galaxies have low rates of star formation, and due to
their diffuse nature, only a small fraction of their original gas
content has been compressed by gravity into new stars.
Galaxies can become irregular during mergers or by gravitational
interactions with larger companions, which stretch and deform them into
the messy shapes we see today.
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