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Old June 9th 12, 05:31 AM posted to sci.astro.amateur
Chris L Peterson
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Default Our galaxy heading for collision with Andromeda Galaxy

On Fri, 8 Jun 2012 20:53:47 -0700 (PDT), signifiespost
wrote:

NASA states that nothing will happen to our Solar system. This is
absurd. The collision will commence after 2 billion years. By that
time, Sun would have turned into a red dwarf star gobbling up all his
planets.


The Sun will become a red giant, not a dwarf. And in so doing, it will
extend to somewhere near Earth's orbit, meaning that it will engulf
Mercury and Venus, and possibly Earth. They could survive that,
however, since the outer region of a red dwarf is so tenuous the
planets could continue to orbit inside it. In any case, however, it is
only the inner three planets at risk of destruction, and their absence
will not change much in the Solar System.

Even otherwise, solar system would perish in countless supernova
explosions that follow the galaxy collision.


When galaxies collide, regions of dust and gas that come together can
form new star forming regions. High mass stars that form there will
produce supernovas within just a few million years of their formation.
But supernovas are only dangerous very locally, and mainly only to
life. Since there will be no life on Earth when the galaxies collide,
there will be nothing to be harmed by any local supernovas (and there
may not even be any that are very close by). Certainly, we observe
many colliding galaxies, and the vast bulk of both parents are not
being affected by star forming regions.