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!
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.
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