Download Irregular Galaxies

Sci. 4-3 Galaxies
Pages 110-113
A. Galaxies- large
groupings of stars in
space held together
by the attraction of
gravity
B. Edwin Hubble classified galaxies
according to their shape. Major
types include spiral, elliptical, and
irregular galaxies
.
1) Spiral galaxies- have a bulge at the center and very distinct
spiral arms,
a) Most galaxies are this type of galaxy.
b) The Milky Way is a
spiral galaxy.
2)Elliptical Galaxies- massive blob of stars
shaped from sphere shape to cucumber
shape
a) only contains old stars
3) Irregular Galaxies- galaxies that don’t fit into the other
classes.
a) Many of these galaxies may have their shape
distorted by neighboring galaxies’ gravity.
C.Nebula- giant clouds of gas and dust
1) Some nebulas are regions where new stars
are formed from gas and dust
D. Globular Cluster- groups of older stars that look like a ball
of stars
1) Globular stars clusters are found in the halos of
spiral galaxies and in elliptical galaxies.
E. Open Clusters- groups of stars that are
usually located along the spiral disk of a galaxy.
F.Origin of Galaxies
1) Because light travels at a
certain speed, observing distant
galaxies is looking back in time.
Scientists look at distant galaxies
to learn what early galaxies look
like.
G. Quasars- a starlike source of light that is extremely far away
1) Quasar may be the earliest types of galaxies ever formed
2) Quasar may have enormous black holes at their center
3) Quasars are among the most powerful energy sources in the
universe.