ACTIVATING STRATEGY:

On your notes write out your address…

Now what country…

What continent…

What planet…

What galaxy?

After today’s lesson, you

should be able to answer all of

these questions and more!

HOW IS OUR SOLAR SYSTEM

POSITIONED IN THE MILKY WAY

GALAXY AND THE UNIVERSE?

S6E1b. Describe the position of the solar system in the Milky Way Galaxy and

the universe.

THE BIG BANG THEORYThe most commonly accepted theory today of the formation of the universe is the Big

Bang Theory.

The theory states that the universe originated sometime between 10 billion

and 20 billion years ago from an enormous explosion of a small volume of

matter at extremely high density and temperature.

Let’s review the

formation of other

objects within the solar

system.

THE UNIVERSE AFTER ITS BIG BANG…

As millions of years passed, the dense areas

of the universe pulled in material because

they had more gravity. Finally, about 100

million years after the Big Bang, the gas

became hot and dense enough for the first

stars to form. Large clusters of stars soon

became the first galaxies.

Scientists believe that Solar Systems formed

in similar ways. Giant clouds of dust and gas

began to collapse under the weight of its

own gravity. As it did so, the matter

contained within it began to move in a giant

circle, much like the water in a drain moves

around the center of the drain in a circle.

At the center of this spinning cloud, a small

star began to form. This star grew larger

and larger as it collected more and more of

the dust and gas that collapsed into it.

Further away from the center of this mass where

the star was forming, there were smaller clumps

of dust and gas that were also collapsing.

The star in the center eventually ignited forming

our Sun, while the smaller clumps became the

planets, minor planets, moons, comets, and

asteroids.

In short, after the Big Bang,

dense clouds of gas and dust

from the “bang” either collapsed

or stuck together to form the

parts of the universe we know

today.

The Universe contains billions of galaxies, each

containing millions or billions of stars.

Therefore, the galaxy in which our solar system

and essentially all of us live, is just one of

billions.

Come up with a comparison of our galaxy

within the universe.

Our galaxy is called __________________.the Milky Way Galaxy

THE MILKY WAY GALAXY

Contains single

star systems,

double stars, and

dust and gas

It is a spiral galaxy

because it has

spiral arms that

wind outward from

the center

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.

• 100,000 light years in diameter

• Our sun orbits the center of the galaxy once every 240

million years

• A barred spiral galaxy

• Contains over 200 billion stars

• Its where we live!!!!!

1B

Galaxy/Galaxies

• A galaxy is a huge

collection of gas, dust,

and stars held together

by gravity. Most

galaxies contain at least

a trillion stars.

• Three types of galaxies:

• Cluster of galaxies

OUR SOLAR

SYSTEM

Our solar system is a

single star system

located on an outer

rim (arm) of the

Milky Way Galaxy.

OUR SOLAR SYSTEM

Here is another view of the location of our

solar system in the Milky Way Galaxy.

STUDY JAMS: THE

SOLAR SYSTEM

EXAMINE THE MILKY WAY

GALAXY AT DIFFERENT SCALES

SCALE OF THE UNIVERSE

ANIMATION

DIGITAL UNIVERSEhttps://www.youtube.com/watch?t=64&v=17jymDn0W6U

Size and Scale of the Universe

Size and Scale of the Universe

Street Address

City and State

County

Continent

Planet

Solar System Location in

Galaxy:

Spiral Arm

Galaxy:

Milky Way

Galaxy Group:

Local Group

Supercluster:

Virgo (or Local)

Size and Scale of the Universe

Image courtesy of The Cosmic Perspective by Bennett, Donahue, Schneider, & Voit; Addison Wesley, 2002

Size and Scale of the Universe

• The region of the Galaxy

within about 20 light-

years of the Sun (40 light-

years diameter)

• A light-year is the

distance that light travels

in one year (~10 trillion

kilometers or 63,000 AU)

• The neighborhood stars

generally move with the

Sun in its orbit around the

center of the Galaxy

• The ‘Solar Neighborhood’

is a vague term not

scientifically defined

Note: the size of the stars in this image

represents their brightness, they would

actually all be specks at this distance

Image credit: Andrew Colvin

Size and Scale of the Universe

• The Milky Way Galaxy

is a giant disk of stars

100,000 light-years

across and 1,000

light-years thick

• The Sun is located at

the edge of a spiral

arm, 30,000 light-

years from the center

• It takes about 250

million years for the

Sun to complete one

orbit

• There are over 200

billion stars in the

Milky Way

Image credit: R. Hurt (SSC), JPL-Caltech, NASA

Size and Scale of the Universe

• About 6.5 million

light-years in

diameter

• Contains 3 large

spiral galaxies --

Milky Way,

Andromeda(M31),

and Triangulum(M33)

-- plus a few dozen

dwarf galaxies with

elliptical or irregular

shapes

• Gravitationally bound

together—orbiting

about a common

center of mass

• Roughly shaped like

a football

Image Credit: Andrew Colvin

Size and Scale of the Universe

• The Local Supercluster is

about 130 million light-

years across

• It’s 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 shapedImage credit: Andrew Colvin