1.
a star cluster that has a loose, disorganized appearance and contains no more than a few thousand stars
2.
a model of the universe in which the average density is less than the critical density needed to halt the expansion causing the universe to expand forever
3.
a model universe in which the average density is great enough to stop the expansion and make the universe contract & collapse
4.
a region of space having a gravitational field so intense that no matter or radiation can escape
5.
a mysterious force that appears to be causing the expansion of the universe to accelerate
6.
the theory that the solar and stellar systems were developed from a primeval nebula
7.
enormously bright, distant galaxy with a giant black hole at its center
8.
a galaxy with a bulge in the middle and arms that spiral outward in a pinwheel pattern
9.
A galaxy shaped like a round or flattened ball, generally containing only old stars
10.
a gigantic region of space in which many groups and clusters of galaxies are packed more closely together than elsewhere in the universe
