Galaxies and the Universe- pg. 81

BIG, I MEAN

BIG

Edwin Hubble

(1889-1953)

• Discovered that the Milky Way galaxy is not alone!

• Several other galaxies in our expanding universe.

• “Hubble Telescope” named after him

Galaxies• Are made up of

BILLIONS of stars, planets, gas and dust

• Held together by gravity

• 3 basic kinds

What galaxy is our solar system in? The

Milky Way

Galaxy.

400 billion stars!

A spiral galaxy.

• It is about 100,000 light years across

What type of galaxy is the Milky Way?

What are the other kinds of galaxies?

• Elliptical Galaxies• look like flattened

spheres. • Contain billions of

stars but little gas and dust. NEW STARS do not form here.

What is the third type of

galaxy called?• Irregular

Galaxies

• No pattern or shape

Why do scientists study distant

galaxies? • Since light from distant galaxies takes a long time to get to earth, scientists can “see” back in time to learn what early galaxies looked like

What is THE UNIVERSE?

• is made of billions of galaxies

• is mostly empty space

• contains EVERYTHING

Why are there so many craters on the moon and some of the small

planets?

• Atmospheres burn up comets and meteors.

• Small bodies in space have no volcanic activity to “hide” the craters with lava, etc.

A special note for the test:

Class Starter 5/19/06Agenda: Astronomy Review—Test

Monday

• 1. Why do scientist study distant galaxies?• 2. What cannot be made in most elliptical

galaxies? Why?• 3. Do you have your notebook ready to

turn in Monday? Today’s study guide is matched up with Monday’s test. Do it so you can get an A!

What is a comet?

“A dirty snowball”

A chunk of rock and ice, the size of a mountain, that orbits the sun

What are the different stages of a

meteor?

• Meteoroid—chunk of rock IN SPACE

• Meteor—same chunk in our sky

• Meteorite—same chunk on the earth

What are asteroids?

• Millions of small objects in orbit between Mars and Jupiter

• These make up the asteriod belt