Homework #3

1. Homework #3 Homework #3 is due Tuesday, October 9. Includes review problems on Newton’s version of Kepler’s 3rd Law and magnitudes

2. Exam #1 Average: 77.7% (standard deviation of 14.5%) Median: 80% High: 102% Still significant of issues with using inconsistent units (e.g., years, or AU, or km instead of standard MKS or cgs units) Still many unreasonable answers (e.g., masses of 10-20 solar masses (!) for stars)

3. Energy Levels of Molecules Molecules are composed of more than one atom, such as H2, H2O, or CO2 • Molecules have additional energy levels because they can vibrate and rotate

4. Phase Changes • Ionization: stripping of electrons, changing atoms into plasma (+ and – ions) • Dissociation: breaking of molecules into atoms • Evaporation: breaking of flexible chemical bonds, changing liquid into solid • Melting: breaking of rigid chemical bonds, changing solid into liquid

5. Moon Landing Hoax and Flat Earth Debate! Did humans really land on the Moon? A surprisingly high fraction of people born post-1969 believe it was a hoax by NASA. Some people think the Earth is flat. What do you think? We will debate this in class on Thursday, October 18, so start gathering your arguments now. If you are not here today (but reading this) let me know what side you want to be on.

6. Moon Landing Hoax and Flat Earth Debate! Resources: Pro-landing: http://www.badastronomy.com/bad/tv/foxapollo.html http://pirlwww.lpl.arizona.edu/~jscotti/NOT_faked/ http://www.braeunig.us/space/hoax.htm http://www.clavius.org/ Pro-hoax: http://www.bibliotecapleyades.net/luna/esp_luna_30.htm http://www.apfn.org/apfn/moon.htm Just about any youtube video…….

7. 10 Minute Presentation • Starting in November, each of you will work in pairs to give a 10 minute presentation on a recent astronomy press release of your choosing • Choose a partner and a press release article, and e-mail me the info (first-come, first-serve for articles) • If you cannot find a partner, let me know and I will pair you with someone (but start looking for articles now)

8. 10 Minute Presentation • Worth 10% of your course grade: 8% presentation 2% participation - you must ask at least two relevant questions to one of your classmates - no trivial questions, must be well thought-out - don’t all ask on the last day! • This is a team effort, so both are responsible equally for the final grade (other than participation)

9. 10 Minute Presentation • 8% presentation - is it at least 10 minutes (5 minute/person)? (4%) - does it incorporate at least two physical/astronomical concepts we have discussed in class? (2%) - did you discuss future work that can build on this result? (2%) I will also give you (ungraded) feedback on your public speaking/presentation style after your talk via e-mail.

10. 10 Minute Presentation • Choose any astronomy topic you wish (although you might feel more comfortable choosing a topic we have already discussed or will discuss in class) - clear the topic with me first • Work must be from 2017 or 2018 (last 12 months) • Use google to find press releases: “NASA press release” “Spitzer press release” “Hubble press release” “astronomy press release” “Chandra press release” space.com, astronomy.com, skyandtelescope.com, universetoday.com

11. 10 Minute Presentation • Layout of Powerpoint Presentation: - Title slide with title and authors (of article) - 2-3 slides of background, discussing the problem being addressed in the press release - use your textbook, Wikipedia, and me - must provide more information than is given in the press release - 1 slide discussing how data was collected (if applicable) - telescope used, wavelength or energy range

12. 10 Minute Presentation • Layout of Powerpoint Presentation: - 2-4 slides describing the key results of the press release - images help a lot - 1 summary slide with key results and why this is interesting - 1 slide with future work discussion 7-10 slides total, or about 1-1.5 minutes a slide is a good pace Practice it in real time out loud a few times before giving it for real!

13. This Week in Astronomy Two small robots from the Hayabusa2 mission (Japan) are currently hopping around the surface of asteroid Ryugu. http://www.hayabusa2.jaxa.jp/en/

14. Mercury • Made of metal and rock; large iron core • Desolate, cratered; long, tall, steep cliffs • Extremely tenuous atmosphere (including water!)

15. Much smaller than Earth: 38% (diameter) and 5% (mass)

16. High density implies a large iron core.

17. Largest day/night swing in temperature in the Solar System : 520 K

18. Surface similar in appearance to Earth’s Moon. Better imaging coming from BepiColombo (2019).

19. Venus • Nearly identical in size to Earth; surface hidden by clouds • Hellish conditions due to an extreme greenhouse effect • Even hotter than Mercury: 460C, day and night

20. Earth’s near twin in size, but scorching hot (greenhouse effect).

21. A Venusian day lasts longer than a Venusian year! Rotation speed only 6.5 km/hr – a moderate walking pace

22. Normal ‘prograde’ rotation of planets. Planet spins counter-clockwise as viewed from above. Same orientation as orbital motion.

23. Venus spins clockwise in ‘retrograde’ rotation. Sun rises in the west and sets in the east every 117 Earth days. Synodic period with Earth almost exactly 5x solar day on Venus – tidal resonance or coincidence?

24. No evidence of plate tectonics. Volcanoes have left their marks on 85% of Venus, with lava plains, lava domes, large shield volcanoes, and extremely long lava channels. The rest of the surface is covered with ranges of deformed mountains. Magellan radar imaging

25. Actual view of Venus’s surface by Soviet lander Venera 13 before it was crushed after 127 minutes by the 89 Earth atmosphere pressure. Thunder and lightning was detected.

26. Earth Earth and Moon with sizes shown to scale (Moon about ¼ diameter of Earth) • An oasis of life • The only surface liquid water in the solar system • A surprisingly large moon

27. Density less than that of Earth

29. Far side of the Moon lacks maria, and is more heavily cratered. More bombardment since it does not have Earth to protect it like the near side of the Moon.

30. Mars • Looks almost Earth-like, but don’t go without a spacesuit. • Giant volcanoes, a huge canyon, polar caps, more • Water flowed in distant past; could there have been life?

31. One Martian day nearly the same length as one Earth day.

32. More comfortable than Tuscaloosa in summer, not so nice in winter.

33. Viking orbiter Polar ice caps composed of water ice and carbon dioxide (CO2) ice. Ice cap shrinks and grows during the Martian seasons.

34. Mount Olympus – 3 times as high as Everest, 600 km across. The largest volcano known in the Solar System.

35. Viking - 1977

36. Mars Global Surveyor - 2001 Viking - 1977

37. Galle crater on Mars

38. Valles Marineris – 4000 km long, 200 km wide, 7 km deep Rift valley, formed by cracking the crust along a fault line.

39. Moons of Mars gravitationally locked in a 1:1 resonance Densities 1.8 g/cm3 and 1.9 g/cm3, like asteroids – captured?

40. A view from Viking 1

41. A view from Pathfinder Clear evidence for miniature Bigfoot Sunset on Mars

42. View from Spirit rover

43. Iron meteorite spied by Opportunity rover – September 16, 2010

44. Mössbauer spectrometer mounted on Opportunity's robot arm, a patch of the tiny spherules ("blueberries“) -- received close examination and have now been identified as hematite (Fe2O3, Iron Oxide). Hematite as a major compositional phase in the spherules supports their formation via precipitation, rather than as impact-related fallout. Further evidence of liquid water in Mars’ past!

45. Jupiter • Much farther from Sun than inner planets • Mostly H/He, solid core; no solid surface • >300 times more massive than Earth • Many moons, rings

46. Jupiter spins very fast  more oblate

47. Much less dense than inner rocky planets.

48. Jupiter’s moons can be as interesting as planets themselves, especially Jupiter’s four Galilean moons. All moons have synchronous orbits (always keep same side facing Jupiter). • Io (shown here): active volcanoes all over • Europa: possible subsurface ocean • Ganymede: largest moon in solar system • Callisto: a large, cratered “ice ball”