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Read each slide then use the red or some underlined

words to complete the organizer.

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Did it start as a bang!

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The Expanding Universe

A. The Big Bang Theory defined:

Idea that all matter began

in an infinitely small

point and exploded out in

all directions

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UNIVERSELet’s start out big and work our way down

VIRGO SUPER CLUSTER

LOCAL GROUP

GALAXY: BILLIONS OF STARS, DUST AND GAS

HELD TOGETHER BY GRAVITY

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Universe

ALL space and everything that is in it.

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Supercluster

Virgo

Size and Scale of the Universe

• The Virgo Supercluster is about

130 million light-years across

• A huge cluster of thousands

upon thousands of galaxies

• Largest cluster is the Virgo

cluster containing well over a

thousand galaxies

• Clusters and groups of galaxies

are gravitationally bound

together, however the clusters

and groups spread away from

each other as the Universe

expands

• Roughly pancake shaped

Image credit: Andrew Colvin

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• ________________ was an astronomer in the 1920s who

gathered many pictures of galaxies

Who knew?

• noticed they all didn’t look alike

• decided to classify them by the way

they looked into 3 types

• “E” or _____________________

• “S” or _____________________

• “SB” or ____________________

Spiral

Barred Spiral

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Galaxy

Billions of stars, dust, and gas held together by gravity

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Galaxies

• Galaxies are grouped together in clusters.

• The cluster the Milky Way

belongs to is called the Local Group.

•Three types of galaxies:

• Galaxies are labeled according to their shape.

• Cluster of galaxies

Elliptical Spiral Irregular

Three types of galaxies:

The Hubble

Tuning Fork

Where do we live? Earth’s

Galaxy—and Other types

• The cluster the Milky

Way belongs to is

called the Local

Group.

• Cluster of galaxies

Spiral Galaxies

• Spiral Galaxies

defined: Circular

galaxies that have

arms curve outward

from a central hub.

–Arms are made up of

stars and dust

• Spiral galaxies!!

Illustration/draw and label:Spiral arm

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Elliptical Galaxies

Most common type of galaxy; large three-dimensional

galaxy shaped like a round or flattened ball, generally containing only old stars

-Contain mostly older and dimmer stars.No bright nucleus at their center. Elliptical galaxies are

represented by the letter E

Divided into seven subgroups according to their shape.

These subgroups are labeled E0 to E7. E0 galaxies

nearly circular in shape while E7 galaxies are

extremely elongated or stretched out.

Illustrate / Draw Elliptical

Irregular Galaxies

• Come in many different

shapes and are smaller

and less common

• Irregular Galaxies - No

regular shape, includes

nebulas, with no central

bulge or spiral arms.

Illustrate/ Draw:

Earth’s Galaxy is …

• Galaxy: A large group of

stars, gas, and dust held

together by gravity.

• Milky Way: Our

galaxy which

contains about 200

billion stars and

many nebulas

• Spiral Galaxies

The Milky Way Galaxy

▪ Why is our galaxy called the Milky Way?

▪ Thousands of years ago people thought the

stars appeared as a patchy band of light

like a flowing river of milk, thus the name

Milky Way.

▪ Also, the word galaxy comes from the

Greek word gala, meaning milk.

The Milky Way Galaxy

• The Milky Way is the galaxy that contains our Solar

System which is just one of the several galaxies of the

universe.

• This name derives from its appearance as a dim

"milky" glowing band arching across the night sky, in

which the naked eye cannot distinguish individual stars.

• Its where we live!!!!!

Milky Way Facts:

• The Milky Way is a barred

spiral galaxy, about 100,000

light-years across. If you could

look down on it from the top,

you would see a central bulge

surrounded by four large spiral

arms that wrap around it.

Milky Way Facts

• The Milky Way also contains two significant minor

arms, as well as two smaller spurs. One of the

spurs, known as the Orion Arm, contains the sun

and the solar system. The Orion arm is located

between two major arms, Perseus and Sagittarius.

• Our sun orbits the center of the galaxy once every

240 million years

• Contains over 200 billion stars

Solar System

Our star (Sun), the planets, many

moons, and other small bodies that

ALL travel around the Sun

Solar System

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What do we see in the sky?• The stars move in the sky but

not with respect to each other

• The planets (or “wanderers”) move differently from stars

– They move with respect to the stars

– They exhibit strange retrograde motion

• What does all this mean?

• How can we explain these movements?

• What does the universe look like?

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The Great Debate! •Heraclides (330 B.C.)

developed the first Solar System model, beginning of the geocentric versus heliocentric debate

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Timeline

Copernicus

1473-1543

Tycho

1546-1601Kepler

1571-1630

Galileo

1564-1642 Newton

1642-1727

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Geocentric (Ptolemaic) System

•The theory (in Greek, geo means earth), which maintained that Earth was the center of the universe, usually referring to the system of Claudius Ptolemy.

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Geocentric (Ptolemaic) System

•The accepted model for 1400 years

•The earth is at the center

•The Sun, stars, and planets on their spheres revolve around the earth: explains daily movement

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Geocentric (Ptolemaic) System cont’…

•To account for unusual planetary motion epicycles were introduced

•Fit the Greek model of heavenly perfection – spheres are the perfect shape, circular the perfect motion

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Illustrate/ Draw model:

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Heliocentric (Copernican) System

•The word "helios" in Greek means "sun." Heliocentric means that the sun is at the center. A heliocentric system is one in which the planets revolve around a fixed sun.

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Helio- continued

•Thus Mercury, Venus, the Earth, Mars, Jupiter and Saturn all revolve around the sun. The moon is the only celestial sphere in this system which revolves around the earth, and, together with it, around the sun.

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Heliocentric (Copernican) System•Sun at center

(heliocentric)

•Uniform, circular motion

–No epicycles (almost)

• Moon orbited the earth, the earth orbited the sun as another planet

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Heliocentric (Copernican) System

•Planets and stars still on fixed spheres, stars don’t move

•The daily motion of the stars results from the Earth’s spin

•The annual motion of the stars results from the Earth’s orbit

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Please Illustrate/ Pick one!

Our Solar System

Our solar system is made up of:

• Sun

• Nine planets

• Their moons

• Asteroids

• Comets

• Meteoros

Read Only!

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We are part of the Earth

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Continent of North America

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Location of United States

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Georgia is a state in the Southeastern United States.

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Marietta is a city located in central

Cobb County, Georgia, United States

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Follow the arrows to fill in the blanks

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• KEY CONCEPTS AND SUMMARY

• When we look at distant galaxies, we are looking back in time. We have now seen galaxies as they were when the universe was about 500 million years old—only about five percent as old as it is now. The universe now is 13.8 billion years old. The color of a galaxy is an indicator of the age of the stars that populate it. Blue galaxies must contain a lot of hot, massive, young stars. Galaxies that contain only old stars tend to be yellowish red. The first generation of stars formed when the universe was only a few hundred million years old. Galaxies observed when the universe was only a few billion years old tend to be smaller than today’s galaxies, to have more irregular shapes, and to have more rapid star formation than the galaxies we see nearby in today’s universe. This shows that the smaller galaxy fragments assembled themselves into the larger galaxies we see today.