Some_Orbit_stuff - Do all spiral galaxies spin in the same...

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Do all spiral galaxies spin in the same direction and why? Why do galaxies rotate in the first place? The answer goes back to the formation of the universe, when matter raced outward in all directions. Clumps eventually formed, and these clumps began to interact gravitationally. Once stuff moved off a straight course and began to curve toward something else, angular momentum, or spin, set in. The laws of physics say angular momentum must be conserved. "Masses of material from which galaxies were formed had an initial amount of angular momentum," explains Rick Perley of the National Radio Astronomy Observatory. As a developing galaxy's gas, dust and stars contract into a smaller region of space, it all spins faster -- just as a skater twirls more rapidly by pulling her arms in. Rings and disks are common in astronomy. When a cloud collapses, the conservation of angular momentum amplifies any initial tiny spin of the cloud. As the cloud spins faster and faster, it collapses into a disk, which is the maximal balance between gravitational collapse and centrifugal force created by rapid spin. The result is the coplanar planets, the thin disks of spiral galaxies, and the accretion disks around black holes. The direction that the Milky Way (our galaxy) spins depends on your perspective. For example, take a top and spin it clockwise on a glass table. Then look at the spinning top from below the glass table - it will appear to spin counter-clockwise now. Or similarly, draw an arrow on a piece of paper in the clockwise direction, then
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This note was uploaded on 12/28/2009 for the course 460 101 taught by Professor Swisher during the Fall '09 term at Rutgers.

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Some_Orbit_stuff - Do all spiral galaxies spin in the same...

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