Download 2. Universe and galaxies

Date:
Entry:
Galaxies and
the Universe
Pg. 394 - 399
1. The Universe
• A. space and everything in it
• B. Contains billions of galaxies
and lots and lots and lots of
empty space
How Big is it?
(don’t copy until I tell you to
start)
It would take 2 million years to
reach the next closest galaxy.
• If our galaxy were the size of a
dime, the Andromeda Galaxy, our
closest neighbor, would be about
half a meter away. The rest of the
universe, as far as astronomers
can see, would extend for about 2
kilometers (1.2 miles) in all
directions.
• If a space ship could explore the
area around one star every
minute it would still take nearly a
million years the explore every
star in our galaxy.
start copying here
2. Origin of the Universe, 3 theories
• A. steady state theory.
• I. the universe always has been
and always will be the
same as it is now.
• B. the oscillating model.
• I. began by expanding.
• II. the expansion slowed and the
universe contracted.
• II. Then process began again,
oscillating back and forth.
(Like an oscillating fan)
• C. most excepted big bang theory.
• I. The universe started with a big
bang and has been
expanding ever since.
• II. Exploded about 13.7 billion
years ago.
• III. The entire universe began to
expand at the same time.
• IV. Supported by the fact that
most things in the
universe are moving
away from a central point
• V. Whether the universe will
expand forever or stop
expanding is still
unknown.
http://www.learn360.com/ShowVid
eo.aspx?lid=26813047&SearchTex
t=Big+Bang+Theory&ID=754560
3. Galaxies
• A. Giant structures containing
I. billions of stars, planets, lots of
gas, and dust, held together by
gravity.
• B. our solar system is in the
Milky Way Galaxy
• C. separated by millions of lightyears.
• I. A light-year is the distance
light travels in one year.
• II. About 9.5 trillion km (5.8
trillion miles) at the speed
of 300,000 km per
second
III. Traveling at the speed of light, it
takes 4.2 years for light from
the next closest star system to
reach Earth
a. about 40 trillion km away
IV. Light from our sun takes 8 min.
• 4. The three major types of
galaxies
A. Spiral Galaxies
• I. have spiral arms that wind
outward from the center.
• II. consist of bright stars, planets,
moons, dust, and gas.
III. 2/3 of spiral galaxies are
Barred spiral galaxies
Spiral Galaxies
B. Elliptical Galaxies
• I. Looks like a flattened football
• II. Most common type
• III. Contains only old stars and very
little dust and gas.
C. Irregular Galaxies
• I. Includes
galaxies
that don't
fit into the
other
categories
• II. have many different shapes.
• III. They are smaller than the
other types of
galaxies.
5. The Milky Way Galaxy
• A. spiral galaxy
• B. contains about one trillion stars.
• C. 100,000 light-years across.
• D. Our Sun is located about 26,000
light-years from the center
• E. All stars orbit around a central
region, or core.
• F. Takes 225 million years for our
solar system to orbit the
center
• G. may have a massive black
hole at its center.
• H. black hole more than 2.5
million times more
massive then the Sun.
Milky Way from La Silla
Taken from a farm in Iowa
Interesting fact:
• Ancient Greeks saw a milky belt
in the southern night sky and
they attributed its origin to Hera
the goddess. While nursing
Heraklis she spilled some of her
milk in the sky - and that milk
created the Milky Road to
Heaven! This is how they called
our Galaxy!
• http://www.learn360.com/ShowVideo.aspx
?lid=26813047&SearchText=milky+way+g
alaxy&ID=132632
Galaxies Review Sheet
Type
Spiral
Elliptical
Irregular
Picture
Information