ASTR-3040: Astrobiology

1. ASTR-3040: Astrobiology Science of Life in the Universe Day-2

2. Homework -1 • Due Tuesday Jan. 25 • Chapter 2: • 1, 3, 16 • 23, 24, 26 • 29, 30, 33 • 44 • 53, 54, 56 • The appendices will be useful

3. Today Activity 1 Activity 2 ?

4. Hallmarks of Modern Science 1. Modern science seeks explanations for observed phenomena that rely solely on natural causes. 2. Science progresses through the creation and testing of models of nature that explain the observations as simply as possible. 3. A scientific model must make testable predictions about natural phenomena that would force us to revise or abandon the model if the predictions do not agree with observations.

5. Modern Science • Occam's Razor • William of Occam (1285 - 1349)‏ • K.I.S.S. • Verifiable Observations • UFOs vs. Einstein Theory of Relativity • Science, Nonscience, Pseudoscience • Objectivity • Scientific Theory • Newton, Darwin, Einstein

6. Gravity • 1666 – Newton • Apple & tree ==> Moon & Earth • Universal Law of Gravitation • Every mass attracts every other mass through a force called gravity. • Directly proportional to product of masses. • Inversely proportional to square of distance between them.

7. G = 6.67 X 10-11 m3/kgs2 Force is in Newtons F = ma (kgm/s2)‏

8. Gravity • But, do we REALLY understand gravity? • Einstein ... space-time

10. Project • http://www.ulalaunch.com/docs/product_sheet/DeltaIVPayloadPlannersGuide2007.pdf • This is the Delta-IV payload guide overview. 20MB. • Planetary quarantine program.

11. The Universe and Life The Universe is vast and old. The elements of life are widespread. The same physical laws operate throughout. The Cosmological Principle There's nothing special about Earth

12. Compared to the universe, the Earth is less than a grain of sand on a beach

13. A Vast Universe • The universe is vast. • We need to handle great distances and long times. • We can do this through the travel time of light. • Light travels 300,000 km every second. • We often use times to denote distances. For example, we may say a friend’s house is two hours away. • Astronomy is a time machine!

14. Light Travel Times Light takes: • 1¼ seconds to arrive from the Moon. • 8.3 minutes to arrive from the Sun. • 5.5 hours to get to Pluto from the Sun. • 4.3 years (yr) to get to the nearest star. • 100,000 yr to cross the galaxy. • 2.9 million yr to get to the nearest big galaxy. • 10 billion yr to come from distant galaxies.

23. Energy Content of the Universe

24. History

25. Expansion

26. Time of Human Life

27. Where do Stars Form? Spirals