Chapter 10 Formation of the Solar System

Section 1 Galaxies

Measuring Distance in Space

• A Light year is the length it takes to measure how far light travels in one year.

• Light years were created it determine how far stars are from the Earth

Types of Galaxies

• A galaxy is a large group of stars, dust, and gas.

• Galaxies are classified according to their shape. Edwin Hubble developed the way to do this.

The Three TypesType of Galaxy

Other info

Spiral Bulge in the center with spiral arms.Most galaxies are spiral.

Spiral, con’t.

The milky way is oneNew stars form on the spiral arms

Elliptical

Elliptical Mostly old starsLook like massive blobs of stars

Irregular

Irregular These galaxies are distorted b/c of other galaxies

What is in a Galaxy??

• Huge clouds of gas and dust called NebulasNebulas. A nebulanebula has several jobs. Some might glow, others absorb light and hide other stars. Some reflect starlight.

Nebula cont’d

• Spiral Galaxies usually have Nebula’s, they are good places to form new stars.

Star Clusters

• Globular clusters:Groups of older stars.

• They are found in a ball like halo surrounding spherical galaxies.

• They are also found near giant elliptical galaxies.

Star clusters cont’d

• Open Clusters: closely grouped stars usually located along the spiral disc of a galaxy.

Interstellar Medium

• The material that is between a galaxy’s stars is called interstellar medium, (clouds of gas and dust).

• Irregular and spiral galaxies have more interstellar medium than elliptical ones.

And then…..

• Scientists look to other galaxies to learn about what early galaxies looked like.

• Quasars, very powerful energy sources, may be caused by black holes