GalaxiesGalaxies

What are galaxies?What are galaxies?

► They are large They are large groups of stars. groups of stars.

► The spiral galaxy The spiral galaxy shown is the shown is the Andromeda Galaxy. Andromeda Galaxy.

► It is 2 million light It is 2 million light years from us.years from us.

Types of GalaxiesTypes of Galaxies

►There are three main types of There are three main types of galaxies. galaxies.

►Spiral: It has a nucleusSpiral: It has a nucleus►Elliptical: It is a bright ball and is Elliptical: It is a bright ball and is

generally older.generally older.► Irregular: It has no specific shape.Irregular: It has no specific shape.

Spiral GalaxiesSpiral Galaxies

► There are your There are your “normal” spiral “normal” spiral galaxies.galaxies.

Spiral cont’dSpiral cont’d

SpiralSpiral

► Barred Spiral Barred Spiral Galaxies appear to Galaxies appear to have a bar through have a bar through the center.the center.

Elliptical GalaxiesElliptical Galaxies

More Elliptical GalaxiesMore Elliptical Galaxies

Irregular GalaxiesIrregular Galaxies

Irregular Galaxies cont’dIrregular Galaxies cont’d

Galaxy EvolutionGalaxy Evolution

► Some galaxies can Some galaxies can appear to evolve appear to evolve over time.over time.

ClassificationClassification

Other FactsOther Facts

► There are at least There are at least 20 other galaxies in 20 other galaxies in our “local group.our “local group.

►Galaxies rotate Galaxies rotate counterclockwise.counterclockwise.

► The diameter of a The diameter of a galaxy can be galaxy can be 100,000 light years 100,000 light years across.across.

The Milky WayThe Milky Way

►Our Galaxy is called Our Galaxy is called the Milky Way.the Milky Way.

The Milky WayThe Milky Way

► The Milky Way is a The Milky Way is a bright line of stars bright line of stars stretching across stretching across the night sky. the night sky.

► It is easier to see It is easier to see when you are far when you are far from bright city from bright city lights. lights.

Milky Way cont’dMilky Way cont’d

► It contains over 100 It contains over 100 Billion Stars.Billion Stars.

Milky Way cont’dMilky Way cont’d

► It has millions of It has millions of nebulae and is an nebulae and is an example of a spiral example of a spiral galaxy. galaxy.

►Our sun is located Our sun is located on a minor arm of on a minor arm of the Milky Way.the Milky Way.

► The Milky Way is The Milky Way is about 100,000 light-about 100,000 light-years in diameter years in diameter and 10,000 light-and 10,000 light-years thick. years thick.

► There are about 2 x There are about 2 x 10 11 stars in the 10 11 stars in the Milky Way. Milky Way.

Other facts about the Milky Other facts about the Milky Way:Way:

►The Milky Way is a spiral galaxy that The Milky Way is a spiral galaxy that formed about 14 billion years ago. formed about 14 billion years ago.

► It takes the sun roughly 250 million It takes the sun roughly 250 million years to orbit once around the Milky years to orbit once around the Milky Way. Way.

►The Earth is about 26,000 light years The Earth is about 26,000 light years from the center of the Milky Way from the center of the Milky Way Galaxy Galaxy