1. Susan CartwrightOur Evolving Universe1

2. Susan CartwrightOur Evolving Universe2 l galaxies  observation of distant galaxies  detailed study of nearby galaxies and Milky Way l stars  detailed study of Sun  studies of stellar clusters  spectroscopic observations  evidence for nucleo- synthesis, age, etc. n Probably some of the material in this course is wrong l we just don’t know what

3. Susan CartwrightOur Evolving Universe3 WMAP

4. Susan CartwrightOur Evolving Universe4 Ken Nollett, Caltech

5. Susan CartwrightOur Evolving Universe5 Simulation by the Los Alamos theoretical astrophysics group

6. Susan CartwrightOur Evolving Universe6

7. Susan CartwrightOur Evolving Universe7

8. Susan CartwrightOur Evolving Universe8 Note that the most common elements in your body all occur in the top ten, formed by a variety of mechanisms (most obvious absentees are calcium and phosphorus) production dissemination

9. Susan CartwrightOur Evolving Universe9 n We have “friendly” nuclear physics l 2 H is stable, but 2 He isn’t  stars work! l 12 C has an energy level at just the right place  carbon is a common element l supernovae explode  heavy elements are incorporated into new stars and planets

10. Susan CartwrightOur Evolving Universe10 n Why look for physics reasons? l anthropic principle arguments less fruitful  useful scientific theories explain existing data and make testable predictions  leads to deeper understanding of nature  more elegant/satisfying

11. Susan CartwrightOur Evolving Universe11 n Theory and observation (cratering record) suggest planets of solar system formed by accretion l dust grains collide and stick to form successively larger bodies l probably fairly easy process if stars form from dust-rich material

12. Susan CartwrightOur Evolving Universe12 Mike Ressler, NASA/JPL