Why Are There Stars?
Why do we have stars in are universe?
Stars (and our Sun) are the result of matter being
attracted to each other. Imagine that in the early history
of the universe, there were just atoms. Since space is essentially
frictionless, these atoms move around freely. Now some atoms might
come into contact with each other and they might stick because
electromagnetic forces tend to allow atoms to stick to each other.
If enough of these atoms adhere to each other, then they will
develop enough mass to have a measurable gravity. The gravitational
forces are very long ranged so that clump of atoms will now start
attracting other clumps of atoms until a big mass is developed. If
the mass is mostly gaseous hydrogen and helium (the very first
atoms) and the mass gets big enough, the gravitational force of
all that mass going inward will start the nuclear reaction that
causes stars to emit heat and light. You can imagine that this
can happen anywhere in the universe where there are lots of these
gases clumping together. And so we see stars.
Greg (Roberto Gregorius)
We have stars because that is the most natural way or galaxies
and the universe to be. Matter gets formed and immediately tries
to galvanize in the simplest way possible. So with the help of gravity,
matter (hydrogen at first) gathers together and is held together by
gravity to form stars.
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Update: June 2012