What are Galaxies

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What are Galaxies?
What did the first galaxies look like? To help
answer this question, the Hubble Space Telescope
has just finished taking the Hubble Ultra Deep
Field (HUDF), the deepest image of the universe
ever taken in visible light. Pictured above, the
HUDF shows a sampling of the oldest galaxies ever
seen, galaxies that formed just after the dark
ages, 13 billion years ago, when the universe was
only 5 percent of its present age. The Hubble
Space Telescope's NICMOS and new ACS cameras took
the image. Staring nearly 3 months at the same
spot, the HUDF is four times more sensitive, in
some colors, than the original Hubble Deep Field
(HDF). Astronomers the world over will likely
study the HUDF for years to come to better
understand how stars and galaxies formed in the
early universe.
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Galaxies

• enormous groups of stars with black holes at its
  center.
• 80-120 billion in the Universe

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3 types of Galaxies

• 1 Spiral
• have centers made up of very bright stars
  spiral arms that branch out from the center
• -The sun and all of the planets in the SS belong
  to the Milky Way Galaxy.
• -The MWG made up of about 300 billion stars.
• -Most stars are in its center and the rest in
  its arms.
• -The sun is on an arm.

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• 2 Elliptical
• Small
• shaped perfectly round or oval
• Stars are older

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• 3 Irregular
• stars are much smaller and fainter
• Most common galaxy

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• The sun and all of the planets in the SS belong
  to the Milky Way Galaxy.
• It is one of 17 galaxies that make up the Local
  Group.

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• The Milky Way is a band of stars (millions) that
  extends from the center of the Milky Way Galaxy.

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• Most Stars in the galaxy are binary stars.
• They are pairs of stars that revolve around each
  other.
• Stars can also be found in small groups called
  clusters.

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