1. Warm Up May 20, 2013 Place 10 dots on the uninflated balloon. Then inflate the balloon and look at what happens to the distance between the dots. How is this like an expanding universe?

2. Agenda Warm Up Correct HW & Worksheet “Powers of 10” Video 15.5 notes Pass out Exam Studyguide Cool Down

3. 15.5 The Expanding Universe The Big Bang is the most widely accepted explanation for how the universe began. It states that around 15 billion years ago, there was a huge explosion where the entire universe was born and it has been expanding ever since.

4. How do we know this? We look at the positions of galaxies. Edwin Hubble discovered that galaxies are moving away from us (like the dots on your balloon in the warm up). Hubble’s Law – the further away a galaxy is, the faster it is moving away from us.

5. Cosmic Background Radiation This type of electromagnetic radiation was detected by a radio telescope in the 1960’s and was determined to be energy leftover from the Big Bang.

6. Formation of Our Solar System Step One: The material in a Solar Nebula was pulled together by gravity and nuclear fusion began giving birth to our sun. Step Two: The planets began to form as small objects called planetesimals. Step Three: Since temperatures are so high near the sun, gases escape this region and leave small rocky planets. Further from the sun, where it is cooler, these gases form the Gas Giants.

7. What does the future hold? One idea is that universe will continue to expand and get colder forever in a “Big Chill” Or, it may expand to a point and then remain the same. Another idea is that gravity will eventually pull everything back together in a “Big Crunch”.

8. Dark Matter & Dark Energy Dark Matter is matter that does not give electromagnetic radiation. So we cannot “see” or detect it. Dark Energy is an undetectable source of gravity used to explain the fact that the universe appears to expand faster and faster.

9. Homework Title: Dark Energy vs. Dark Matter Double Bubble Map 15.5 Vocab (7 words) P. 627 #1a-c, #2a-c, & #3a-c Cool Down The studyguide will be posted on Sharepoint if you want to print it out and start reviewing.