1. ORION Constellation

2. Orion

3. Orion the Hunter Orion was thought to be a great hunter, always traveling with his faithful hunting dogs (Canis Major, Canis Minor). Killed by the Scorpion (Scorpio) and thus lives on the opposite side of the celestial sphere. May also be chasing the Pleiades (the Seven Sisters) closer to him in the sky.

4. Orion’s Major Stars Alpha – Betelgeuse (mag. 0.45) ◦ Red Giant (dying star) which appears slightly redish-yellow Beta – Rigel (mag. 0.18) ◦ Blue giant (early to midlife) which appears slightly blueish-white

5. Orion

6. Orion’s Objects M42 – The Orion Nebula (Telescope)

7. Orion’s Objects Horeshead & Flame Nebula (Hubble)

8. Orion’s Objects Barnard’s Loop

9. Extra Credit (+3) 1. Clearly photograph entire constellation 2. Identify Rigel, Betelgeuse, M42

10. COMPARATIVE PLANETOLOGY: VENUS AND MARS Chapter 22

11. Venus & Mars Two most similar planets to Earth ◦ Location ◦ Size and Shape ◦ Atmosphere ◦ Interior Structure Life is impossible on both

12. Venus

13. Mars

14. The Rotation of Venus Almost all planets rotate in the same sense as orbital motion. Exceptions ◦ Venus, Uranus

15. The Rotation of Venus Venus rotates clockwise, with period slightly longer than orbital period. Possible reasons: ◦ Off-center collision with massive protoplanet ◦ Tidal forces of the sun on molten core

16. UV image The Atmosphere of Venus Extremely inhospitable: ◦ 96 % - CO 2 ◦ 3.5 % - N 2 ◦ 0.5% - H 2 O, HCl, HF

17. UV image The Atmosphere of Venus 4 thick cloud layers ◦ surface invisible from Earth Very stable circulation patterns with high- speed winds (up to 240 km/h) Very efficient greenhouse Extremely high surface temperature up to 745 K (880 F)

18. The Surface of Venus Early radar images already revealed mountains, plains, craters. ◦ More details from orbiting and landing spacecraft:

19. Lava Flows Young, uneven lava flows (shown: Lava flow near Flagstaff, AZ) show up as bright regions on radar maps.

20. Radar Map of Venus’s Surface Scattered impact craters Surface features shown in artificial colors Volcanic regions Smooth lava flows

21. Surface Features on Venus Smooth lowlands Highland regions: Maxwell Montes are ~ 50 % higher than Mt. Everest!

22. Craters on Venus

23. Nearly 1000 impact craters on Venus’s surface ◦ Surface not very old. No water on the surface; thick, dense atmosphere ◦ No erosion ◦ Craters appear sharp and fresh

24. Volcanism on Earth

25. Volcanism on Earth is commonly found along subduction zones (e.g., Rocky Mountains). This type of volcanism is not found on Venus or Mars.

26. Shield Volcanoes Found above hot spots. ◦ Fluid magma chamber, from which lava erupts repeatedly through surface layers above. All volcanoes on Venus and Mars are shield volcanoes

27. Shield Volcanoes Tectonic plates moving over hot spots producing shield volcanoes  Chains of volcanoes

28. Shield Volcanoes The Hawaiian Islands

29. Sapas Mons 250 miles

30. Lakshmi Planum and Maxwell Mountains Radar image Wrinkled mountain formations indicate compression, though there is no evidence of plate tectonics on Venus.

31. A History of Venus Complicated history; still poorly understood. Very similar to Earth in mass, size, composition, density, ◦ no magnetic field  Core solid?

32. A History of Venus Solar wind interacts directly with the atmosphere, forming a bow shock and a long ion tail. CO 2 produced during outgassing remained in atmosphere Any water present on the surface rapidly evaporated

33. A History of Venus Pancake Domes:  Associated with volcanic activity forming coronae Heat transport from core mainly through magma flows close to the surface (  coronae, pancake domes, etc.)

34. Volcanic Features on Venus Baltis Vallis: 6800 km long lava flow channel (longest in the solar system!) Coronae: Circular bulges formed by volcanic activity

35. Mars Roughly half the size of Earth Axis tilted against orbital plane by 25- degrees Very thin atmosphere, mostly CO 2 Rotation period 24 h, 40 min.

36. Mars Seasons similar to Earth ◦ Growth and shrinking of polar ice cap Crust not broken into tectonic plates Volcanic activity (including highest volcano in the solar system)

37. Canals and Life on Mars Early observers believed to see canals on Mars This, together with growth/shrinking of polar cap, sparked imagination and sci- fi tales of life on Mars.

38. Life on Mars No evidence of life on Mars

39. Face on Mars

40. Happy Face Crater Galle Crater, the “happy face crater”

41. The Atmosphere of Mars Even thin Martian atmosphere evident through haze and clouds covering the planet Occasionally, strong dust storms can enshroud the entire planet.

42. The Atmosphere of Mars Very thin: Only 1% of pressure on Earth’s surface 95 % - CO 2 Reddish color of the surface ◦ Most of the Oxygen bound in oxides in rocks

43. History of Mars’s Atmosphere Atmosphere probably initially produced through outgassing. Loss of gasses from a planet’s atmosphere: Compare typical velocity of gas molecules to escape velocity Gas molecule velocity greater than escape velocity  gasses escape into space. Mars has lost all lighter gasses; retained only heavier gasses (CO 2 ).

44. The Geology of Mars

45. Reddish deserts of broken rock, probably smashed by meteorite impacts.

46. The Geology of Mars The surface features on Mars have most recently been explored close-up by the Mars rovers Spirit and Opportunity.

47. The Geology of Mars (2) Northern Lowlands: Free of craters; probably re-surfaced a few billion years ago. Southern Highlands: Heavily cratered; probably 2 – 3 billion years old. Possibly once filled with water.

48. Olympus Mons Highest and largest volcano in the solar system.

49. Tharsis Rise Nearly as large as the U.S. Rises ~ 10 km above mean radius of Mars. Rising magma has repeatedly broken through crust to form volcanoes.

50. Hidden Water on Mars No liquid water on the surface: ◦ Would evaporate due to low pressure. Evidence for liquid water in the past: ◦ Outflow channels from sudden, massive floods

51. Hidden Water on Mars Collapsed structures after withdrawal of sub-surface water Valleys resembling meandering river beds

52. Hidden Water on Mars Central channel in a valley Gullies from debris flows

53. Hidden Water on Mars Hematite concretions in Martian Rocks, photographed by the Mars Rover Opportunity Sedimentary rock layers, formed by rapidly flowing water.

54. Ice in the Polar Cap Polar cap contains mostly CO 2 ice, but also water. Multiple ice regions separated by valleys free of ice.

55. Evidence for Water on Mars Large impacts may have ejected rocks into space. Meteorite ALH84001 ◦ Identified as ancient rock from Mars. ◦ Some minerals in this meteorite were deposited in water

56. The Moons of Mars Phobos Deimos

57. The Moons of Mars Two small moons: Phobos and Deimos. Too small to pull themselves into spherical shape. Dark grey, low density. Very close to Mars ◦ orbits around Mars faster than Mars’ rotation. Probably captured from outer asteroid belt.