In general, everything in
the cosmos is moving apart, but there are some exceptions to this. The nearest
galaxy to our own, Andromeda, is barreling towards us, which means that in 4
billion years or so, it’ll merge with the Milky Way. If we want to see examples
of galaxy collisions, though, we only need look to the deep dark shadows above
us.
The dance of these stellar
museums are violent and sometimes highly destructive; other times, they look
more like a ballet than a mosh pit. If a larger galaxy meets a smaller one, it
devours it and destroys its junior partner – something our own Milky Way has
accomplished at least eleven times.
An image recently released
by NASA and the European Space Agency (ESA) illustrates one such galaxy merger
event, but arguably a more peaceful one. Pictured here in NGC 3256 is a
distorted galactic soup that resulted from the clash of two separate ones that
started colliding around 500 million years ago, around the time complex life on
Earth was just starting to flourish.
As the galaxies involved
were originally of a similar size, they had an equal influence on each other,
which resulted in a somewhat calm merger rather than a winner-takes-all event.
See those tails? They’re
packed with young stars, formed during the collision of some raw material
perfect for forming new thermonuclear furnaces, particularly all that hydrogen.
In fact, as it turns out, in much the same way that asteroid belts in movies
are damned lies, the spaces between stars are probably far, far greater than
you think. After all, the nearest star system to the Sun is still around 4
light-years away.
In fact, NGC 3256 is
referred to as a “starburst galaxy”, in that it’s exhibiting a
far-above-average rate of star formation.
This has resulted in a stellar fireworks show most luminous in the
infrared. Thanks to its face-on orientation, it’s giving astronomers a perfect
opportunity to study how starbursts are borne from such mergers.
The collision, rather
excitingly, is still taking place from our point of view. In a few hundred
million years’ time, their cores will merge fully, and it’ll become one single,
huge elliptical galaxy. Sadly, of course, we won’t be around to see it happen.
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