| Why do the stars orbit each other?
|Question Date: 2013-05-01|
Stars orbit each other, because if two equal
mass objects are in space, then they both orbit
the center of mass of the total system.
Stars orbit because of gravity - stars have
mass, so exert gravity on other stars, just as the
planets orbit the sun (which is, after all, a
star). The galaxy also has a large black hole in
the center that the stars also orbit because of
its gravity. Finally, there is something called
"dark matter" - matter that exerts gravity like
other mass and makes up about 90% of the matter of
the galaxies in the universe, but we have no idea
what it is.
Good question! Stars, and other bodies in the
universe, orbit each other because of
gravitational attraction and conservation of
angular momentum. The physical law of conservation
of momentum basically says that once something is
spinning, it will continue to spin (forever if
nothing interferes). Because the bodies in the
early universe were spinning, they continue to
spin. The orbits of bodies in the universe is sort
of a balance between gravity and momentum. If a
star did not “feel” the gravity of another star
that is was orbiting, it would “fling” off into
space. Conversely, if momentum was not conserved,
the two stars would collapse onto one another due
to gravity. The balance of gravity and angular
momentum results in circular or elliptical orbits.
Stars orbit each other because they exert
gravity on each other. Anything with mass exerts a
gravitational pull on its surroundings, so the
starts are attracted to each other, leading to
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