galaxies sombrero galaxy (spiral) andromeda galaxy (spiral)

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Galaxies Sombrero Galaxy (spiral) Andromeda Galaxy (spiral)

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Page 1: Galaxies Sombrero Galaxy (spiral) Andromeda Galaxy (spiral)

Galaxies

Sombrero Galaxy(spiral)

Andromeda Galaxy(spiral)

Page 2: Galaxies Sombrero Galaxy (spiral) Andromeda Galaxy (spiral)

Galaxies

Page 3: Galaxies Sombrero Galaxy (spiral) Andromeda Galaxy (spiral)

What is a galaxy?• Stars are not uniformly distributed

through the universe but are unevenly clustered into groups.

Page 4: Galaxies Sombrero Galaxy (spiral) Andromeda Galaxy (spiral)

What is a galaxy?• A galaxy is a massive system of

stars, dust, and gas held together by gravity.

• Galaxies contain billions of stars.

Page 5: Galaxies Sombrero Galaxy (spiral) Andromeda Galaxy (spiral)

What is a galaxy?• Within galaxies, are smaller groups

of stars known as star clusters.• A “cluster” is a group of stars inside

the galaxy.

M13 Cluster• in our galaxy• can see with binoculars• over 100,000 stars

Page 6: Galaxies Sombrero Galaxy (spiral) Andromeda Galaxy (spiral)

What is a galaxy?• Hubble identified three types:

SpiralEllipticalIrregular

Page 7: Galaxies Sombrero Galaxy (spiral) Andromeda Galaxy (spiral)

Spiral Galaxy• Shaped like a flattened

disk with a bulging center and “arms” that curve in a spiral pattern

• Rich with dust and gases• New stars are in “arms”• Old stars are in the center• (e.g.) Milky Way

Page 8: Galaxies Sombrero Galaxy (spiral) Andromeda Galaxy (spiral)

Elliptical Galaxy• Shaped like a sphere or

“egg” because stars are close together near the center & farther apart on the outside edges

• Very little dust and gas• Very few new stars• Mostly old stars

Page 9: Galaxies Sombrero Galaxy (spiral) Andromeda Galaxy (spiral)

Irregular Galaxy• No definite shape or

organization• Contains clouds of

dust and gases• Contains a mix of old

and new stars

Page 10: Galaxies Sombrero Galaxy (spiral) Andromeda Galaxy (spiral)

Milky Way• Our solar system is located in a spiral

galaxy called the Milky Way Galaxy.

Page 11: Galaxies Sombrero Galaxy (spiral) Andromeda Galaxy (spiral)

Milky Way

1 – Closest Milky Way “arm”

2 companion galaxies:2 - Large Magellanic Cloud 3 - Small Magellanic Cloud

2

3 1

Page 12: Galaxies Sombrero Galaxy (spiral) Andromeda Galaxy (spiral)

Distances between Galaxies

• Galaxies are so far away that even the closest galaxies appear as fuzzy patches

of light.

Page 13: Galaxies Sombrero Galaxy (spiral) Andromeda Galaxy (spiral)

Distances between Galaxies

• Galaxies are grouped together into clusters, which form superclusters.

• The Milky Way is part of a cluster called the Local Group.

• The farthest galaxies from Earth are about 14 billion light years away.

Page 14: Galaxies Sombrero Galaxy (spiral) Andromeda Galaxy (spiral)

Mind = Blown

Page 15: Galaxies Sombrero Galaxy (spiral) Andromeda Galaxy (spiral)

Big Bang Theory• In the late 1920s, Hubble discovered

that most of the galaxies he observed were moving away from Earth.

• This could only be explained if the entire universe was expanding.

Page 16: Galaxies Sombrero Galaxy (spiral) Andromeda Galaxy (spiral)

Big Bang Theory• The Big Bang Theory states the

expansion of the universe began about 14 billion years ago.

• The universe was a tiny point that contained all the energy and matter of the universe.

• The universe began to expand rapidly, and cool.

Page 17: Galaxies Sombrero Galaxy (spiral) Andromeda Galaxy (spiral)

Big Bang Theory• The universe was too hot to form

elements for several hundred thousand years.

• The universe consisted of radiation and subatomic particles.

• As the universe cooled, hydrogen and helium atoms formed.

Page 18: Galaxies Sombrero Galaxy (spiral) Andromeda Galaxy (spiral)

Big Bang Theory• Galaxies began forming several hundred

million years after the Big Bang.• Clouds of hydrogen and helium possibly

became more dense in some regions.

Page 19: Galaxies Sombrero Galaxy (spiral) Andromeda Galaxy (spiral)

Big Bang Theory• The dense regions began to clump and

form stars.

Page 20: Galaxies Sombrero Galaxy (spiral) Andromeda Galaxy (spiral)

Dark Matter & Dark Energy

• Scientists can calculate how much mass the universe should contain by the way galaxies move through space.

• All the matter they can detect added together is less than the amount needed.– The missing matter is called dark matter.– The missing energy needed to explain the

expansion of the universe is called dark energy.

Page 21: Galaxies Sombrero Galaxy (spiral) Andromeda Galaxy (spiral)

Which is the shape of the Milky Way?

A flat

B elliptical

C irregular

D spiral

12.3 Galaxies

Page 22: Galaxies Sombrero Galaxy (spiral) Andromeda Galaxy (spiral)

How old is the universe thought to be?

A several hundred thousand years

B 1 million years

C 14 billion years

D 63,000 million years

12.3 Galaxies

Page 23: Galaxies Sombrero Galaxy (spiral) Andromeda Galaxy (spiral)

A cluster is a group of ____.

A stars

B solar systems

C galaxies

D planets

12.3 Galaxies

Page 24: Galaxies Sombrero Galaxy (spiral) Andromeda Galaxy (spiral)

The average distance between Earth and the Sun is called a(n) ____.

A light-year

B astronomical unit

C angstrom

D solar unit

SCI 4.c

Page 25: Galaxies Sombrero Galaxy (spiral) Andromeda Galaxy (spiral)

What causes clouds of gas and dust to form clumps in interstellar space?

A solar winds

B gravity

C electrons

D dark matter

SCI 2.g

Page 26: Galaxies Sombrero Galaxy (spiral) Andromeda Galaxy (spiral)

Galaxies have what three shapes?

A cluster, group, and spiral

B supercluster, cluster, and group

C spiral, elliptical, and irregular

D regular, irregular, and flat

SCI 4.a

Page 27: Galaxies Sombrero Galaxy (spiral) Andromeda Galaxy (spiral)

Vocab – Galaxiestext p. 528-534

1. galaxy

2. spiral galaxy

3. Milky Way

4. elliptical galaxy

5. irregular galaxy

6. randomly

7. big bang theory

HIGHLIGHT!!!