Cornell Notes...

1. Cornell Notes... TITLE • This column gets filled out LATER! • Can be key questions about notes • used as study questions for test • Can also be questions about things you did not understand • Notes will go here • from my PowerPoints • Bulleted or outlined information works best • Try not to use long sentences • Avoid paragraphs • Use abbreviations YOU understand

2. A helpful guide... • FOR THESE NOTES ONLY... • I’m going to include some helpful hints on how I organize my notes. • They will be in small boxes off to the side, in bright blue font. • Don’t write those things down.

3. Credit: NASA / WMAP Science Team Formation of the Universe

4. Key vocabulary is bolded and underlined. These are very important! Big ideas or topics are at the top. These should be your sub-headings, with your bullets following below Cosmology • The study of the universe • Its current nature • Its origin and evolution

5. The Universe • Universe is expanding • Which means it had to have a beginning.

6. Usually when I give you lists like this, we will discuss each of them in class. You probably do NOT need to write anything but the title down. How the Universe Began • Theories of how the universe began: • Steady State Theory • Big Bang Theory • Inflationary Model

7. The italicized question does NOT need to be written down. It’s just something to think about. Steady State Theory • Proposes that the universe looks the same on large scales, and has always looked that way • Universe does not change with time • BUT! If the universe is expanding, how can this be true? • New matter is created and added to the universe as it expands

8. Big Bang Theory • NOT an explosion into space • IS an expansion of space with matter along for the ride

9. The Big Bang Model • Consists of a competition between: • Outward momentum of expansion • Inward force of gravity • This is how the universe acts to slow the expansion

10. If there is information written under each bullet in a list, then this is info you should probably have in your notes. B.B.T. - Outcomes of Expansion • Three outcomes for the universe: • Open Universe • Expansion never stops • Closed Universe • Expansion will stop and turn into contraction • Flat Universe: • Expansion will slow to a halt in an infinite amount of time, but never contract

11. Inflationary Model • Version of the Big Bang Model • Universe began as a fluctuation in a vacuum • Expanded very rapidly for a fraction of a second • Settled into a more orderly expansion

12. Research of Theories • Many observational tests can be done to provide support for all theories • Today, evidence weighs in favor of the Big Bang Theory

13. B.B.T. - Present Day • Appears that the rate of expansion slowed for awhile, but is now gathering speed • What is causing this? • Some scientists suggest it is caused by an unknown force • Stronger than gravity • Pushing galaxies apart

14. Looking Back • A trip through space and time to put the B.B.T. in perspective. • Journey to the Big Bang Credit: NASA / WMAP Science Team

15. Hubble image: NASA and ESA Formation of Our Galaxy

16. Stars and Planets • Formed from interstellar clouds • Clouds of dust and gas • Mostly hydrogen and helium gas • Many interstellar clouds are observed along the Milky Way • Have low density • This means their materials are very spread out • BUT they can condense because of gravity • Eventually becomes stars and possibly planets • Hypothesis on how our solar system was created!

17. Collapse of the Cloud • Very slow at first • Speeds up and starts rotating as it collapses • Becomes a rotating disk (solar nebula) • Center of the disk (densest part) eventually becomes the Sun • As the disk cooled, different elements were able to form in solid and liquid states

18. Growth of Objects • As condensing slowed, small particles started to accumulate • These began to merge together to make larger ones • Eventually became hundreds of kilometers in diameter • Called planetesimals

19. Planetesimals • Continued to grow and merge with others • Merges were violent • Sometimes planetesimals were destroyed • Overall result was a small number of large bodies (planets)

20. The Planets • Jupiter formed first • Continued to grow • Saturn was next • Then the other gas planets • None of the planets could get as big as Jupiter because it already had so much of the galaxy’s material

21. Asteroid Belt • Actually just planetesimals that never merged • Stayed between Mars and Jupiter • Jupiter’s gravitational force prevented them from merging. • Asteroid - rocky remnant of the early system • A few kilometers to 1000 kilometers in diameter

22. Meteoroid, Meteor, Meteorite • Meteoroid - any interplanetary object that falls and enters Earth’s atmosphere • Meteor - a meteoroid that burns and produced a streak of light. • Meteorite - a meteoroid that does not burn up completely and part of it hits the ground.

23. Comets • Small bodies with highly eccentric orbits around the Sun • Made of ice and rock • 1-10 km in diameter • Two major clusters of comets: • Kuiper Belt - close to Pluto (30-50 Astronomical Units (AU)) • 1 AU = 149,600,000 km • Oort Cloud - 100,000 AU from the Sun

24. Comets (continued) • When we see comets, it’s because they are within 3 AU of the Sun • Start of evaporate, forming a head and tail • Hale Bopp - last seen in 1997 - will be seen again in 4397 • Periodic Comets - those that repeatedly orbit into the inner solar system • Halley’s Comet - last seen in 1985-86 - will be seen again in 2061 - has a 76 year period

25. Meteor Shower • When Earth intersects a cometary orbit