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The SDSS observes lots of stars. Stars are giant balls of gas
burn hydrogen at their cores. When they run
out of hydrogen, they can burn other elements.
Eventually, their fuel supply runs out and they die.
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A star cluster
Click on the image for
a larger view |
Stars are often found in clusters, hundreds together.
There are many types of clusters. A typical star
cluster, as seen by the SDSS, is shown at the right.
Galaxies are huge collections of stars. Our galaxy, The Milky Way,
may contain up to a trillion stars. No one is exactly sure
how many. Other galaxies are even bigger. Some "dwarf"
galaxies are much smaller.
Galaxies come in different shapes. The three types of galaxies
are spiral, elliptical, and irregular. Examples of each type are
shown below.
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An elliptical
galaxy |
A spiral
galaxy (seen from the front) |
A spiral
galaxy
(seen from the side) |
An irregular galaxy |
Sometimes, galaxies pass close to each other. When they do, their
gravity can cause them to warp. The galaxies can
bend each other, making them look like the pair shown below.
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A close pair of
galaxies |
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