Explanation:
Taken by a telescope onboard
NASA's Swift satellite,
this stunning vista represents the highest resolution image
ever made of the
Andromeda Galaxy (aka M31) - at ultraviolet
wavelengths.
The mosaic is composed of 330 individual images covering
a region 200,000 light-years wide.
It shows about 20,000 sources,
dominated by hot, young stars
and dense star clusters that radiate strongly in
energetic
ultraviolet light.
Of course, the Andromeda Galaxy
is the closest large spiral galaxy
to our own Milky Way, at a distance of some 2.5 million light-years.
To compare this
gorgeous island universe's appearance
in optical light with its ultraviolet portrait, just slide your cursor over
the image.
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