Galaxies

What will we be learning?

•What is a galaxy?
•What are the three major types of galaxies and the characteristics of each?

•What is the name of our galaxy?

•Where is our solar system in our galaxy?

What is a galaxy?

• A galaxy is a large grouping of stars,

gas, and dust in space that are held
together by GRAVITY.

• The largest galaxies contain more

than a trillion stars. Smaller galaxies
may have only a few million.

• Scientists estimate the number of

stars from the size and brightness of
the galaxy.

Contents of Galaxies

Galaxies are made
of stars, planetary
systems, gas
clouds, and star
clusters. NEBULAS
are giant clouds of
gas and dust where NEW STARS may be
forming.

Nebula are found
in spiral galaxies
but not elliptical
galaxies.

Main Types of

Galaxies

Spiral

Elliptical

Irregular

Multiple Choice

What are in galaxies?

• ice and rock

• dust, gas, and stars

• stars and ice

• water and dust

Multiple Choice

What is not a galaxy?

• Optical Galaxy

• Spiral Galaxy

• Elliptical Galaxy

• Irregular Galaxy

Multiple Choice

What are galaxies held together by?

• Gravitational Attraction

• Stars

• Other galaxies

• Dust and Gas

Multiple Choice

A galaxy is a large collection of stars, gas and dust. What is responsible for holding the stars, gas, and dust together in a galaxy?

• heat

• light

• gravity

• friction

Multiple Choice

How many stars are in a galaxy.

• millions or billions

• thousands

• hundreds

• Ten

Properties of

Spiral Galaxies

• Shaped like flattened

disks with one or
more spiral arms.

• Our galaxy, Milky Way, is

a spiral galaxy.

• Our solar system is

located in one of the spiral
arms.

Properties of

Elliptical Galaxies

• Round or elliptical in shape.
• Contain very little gas or dust.
• Because of little gas, no new stars are forming, only old stars.

• The largest and smallest

galaxies are elliptical galaxies.

• About 1/3 of all galaxies.
• Simply massive blobs of stars.

Properties of

Irregular Galaxies

• Do not fit into any other

category.

• Chaotic mix of stars, gas

and dust.

• Usually found near large

spiral galaxies who may
be distorting their shape.

No fixed shape.

Describe the Milky Way Galaxy

• Flattened Disk
• Bulge in Middle
• Fried Egg
• Not solid from edge to edge
• Huge
• 1000-3000 Light Years Thick
• 100,000 Light Years across (Diameter)

Where is our solar system in

our galaxy?

• The Sun and our solar system is

located in one of the outer arms
(Orion’s Arm) of the galaxy. The
distance from the Sun to the center of
the galaxy is about 30,000 light years.

• All objects in the galaxy revolve around

its center.

• The sun and our solar system take

about 240 million years to make one
trip around the center of our galaxy.

Multiple Choice

Which type of galaxy is shown in the image?

• Spiral

• Elliptical

• Irregular

Multiple Choice

Which type of galaxy is shown in the image?

• Spiral

• Elliptical

• Irregular

Multiple Choice

What type of galaxy is this?

• Irregular

• Spiral

• Barred Spiral

• Elliptical

Multiple Choice

Galaxies are classified by their....

• Size

• Density

• Brightness

• Shape

Multiple Choice

Our sun is located on one of the Spiral Galaxy arms.  

• True

• False

Multiple Choice

What type of galaxy is depicted in this image?

• spiral

• elliptical

• irregular

• quasar

Multiple Choice

What type of galaxy is this?

• Spiral

• Elliptical

• Irregular 

• Irrational

Multiple Choice

What type of galaxy is this?

• Spiral

• Elliptical

• Irregular

• Irrational

Multiple Choice

What type of galaxy is this?

• Spiral

• Elliptical

• Irregular

• Irrational

Multiple Choice

What type of galaxy has no defined pattern or shape?

• Spiral 

• Elliptical

• Irregular

• Constellation

Multiple Choice

What is the name of our galaxy? 

• Our galaxy is called the Milky Way galaxy 

• Our galaxy is called the Andromeda galaxy 

• Our galaxy is called the Grand spiral  galaxy. 

• Our galaxy is called the Whirlpool galaxy.

Multiple Choice

The type of galaxy that has few young stars, little gas or dust, and NO arms is a/n

• elliptical galaxy

• spiral galaxy

• irregular galaxy

• barred spiral galaxy

Multiple Choice

The most abundant type of galaxy in the universe is an...

• Spiral Galaxy

• Elliptical Galaxy

• Irregular Galaxy

Multiple Choice

The type of galaxy that is composed of the older stars and low-mass stars.

• Spiral

• Elliptical

• Irregular

• Constellation

Multiple Choice

All stars begin as a __________?

• giant

• black hole

• white dwarf

• nebula

Multiple Choice

Where are we located within our galaxy?

• On one of the spiral arms

• On the outer edge

• In between 2 of the spiral arms

• In the center bulge

Multiple Choice

Which type of galaxy is a flat, rotating disk of billions of stars, gas and dust with a central concentration of stars?

• Spiral

• Elliptical

• Irregular

• Triangular

Multiple Select

Contains the oldest stars.

• Elliptical

• Irregular

• Spiral

Multiple Select

What type of galaxy is pictured here?

• Elliptical

• Irregular

• Spiral