Star GroupsMr. Silva

Ag Earth Science

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

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.

GalaxiesThe 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.

Types of Galaxies

Spiral Galaxy: has a nucleus or bright center with flattened arms that spiral around the nucleus.

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.

Types of Galaxies

Irregular Galaxy: has no particular shape. They are very small and faint. Very little gravitational pull.

The Milky Way

Our galaxySpiral galaxy Has a diameter of 100,000 light yearsOur 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.

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.