The document discusses different astronomical objects including stars, constellations, galaxies, and the Milky Way galaxy. It notes that while stars appear single, most are actually part of binary or triple star systems. Constellations are patterns of stars that appear close together but are actually extremely far apart. Galaxies are large groups of stars, dust and gas bound by gravity, with the Milky Way being the galaxy where Earth is located.

1. Star Groups
Mr. Silva
Ag Earth Science

2. Stars
The visible stars you see at night are only some of
the stars in our galaxy.
Most stars seem to be single stars, but in actuality
they are mostly doubles and triples.
 1/3 are doubles
 ¼ are singles

3. Constellations
Constellations are patterns of starts.
They may look like they are close together but really
they are extremely far apart.
We recognize 88 different constellations.
Named after gods, heroes or fierce animals.

4. Galaxies
The major components of the universe are
galaxies.
They are large groups of stars bound together by
gravitational attraction.
Made up of millions of stars, dust clouds and
gases.
Estimated 50 billion and 1 trillion galaxies in the
universe.
We live in the Milky Way Galaxies.

5. Types of Galaxies
Spiral Galaxy: has a nucleus or bright center
with flattened arms that spiral around the nucleus.

6. Types of Galaxies
Elliptical Galaxy: They are very bright centers and
do not have spiral arms. Have no young stars and
contain very little dust and gas.

7. Types of Galaxies
Irregular Galaxy: has no particular shape. They
are very small and faint. Very little gravitational
pull.

8. The Milky Way
Our galaxy
Spiral galaxy
Has a diameter of 100,000 light years
Our sun is about 30,000 light years from the center.
Revolves at a speed of 250km/s.
Takes 200 million years to make one revolution.

9. Formation of the Universe
The big bang theory- matter was all concentrated in
an extremely small volume
Occurred 12-15 billion years ago.
Galaxies are continuing to move outward.

10. Formation of the Universe
The big bang theory- matter was all concentrated in
an extremely small volume
Occurred 12-15 billion years ago.
Galaxies are continuing to move outward.