Chapter 19-2

1. Chapter 19-2 The Inner and Outer Planets

2. Rocket Science . . .http://www.youtube.com/watch?v=mmlM5XQxdMs

3. The NineEight Planets • The term “planet” is derived from the Greek for “wanderer” (picture not to scale) Source: http://vathena.arc.nasa.gov/curric/space/planets/

4. Planets • Five visible w/o telescope • Mercury, Venus, Mars, Jupiter, Saturn • Nine Eight total • Uranus, Neptune, Pluto • Who is Clyde Tombaugh, and why should you know? • Moons: (define satellite) • Earth’s: Luna, “loony,” werewolves, moonth • Jupiter’s: Galilean (Io, Europa, Ganymede, Callisto) disc. by . . . Galileo Galilei • Saturn’s, Uranus,’ Neptune’s • Pluto’s size ~ Charon’s; considered a binary system

5. Planets & Their Moons

6. The planets, to scale

7. The Terrestrial Worlds

8. Inner Planets: Overview • Inside the asteroid belt • “Terrestrial” planets • Small • Solid surfaces • Composed of rocks & metals • High densities • Few satellites

9. Inner Planets: Mercury • God of commerce, travel & thievery (speed) • Closest to sun • Orbit didn’t behave according to Newton’s predictions on planetary motion • Caused by Vulcan? • Reconciled by Einstein’s General Theory of Relativity

10. Inner Planets: Venus • Ancient goddess of beauty • Bright, beautiful morning/evening “star” • Heavily clouded w/CO2 • Hot, sulfuric acid • Runaway greenhouse effect

11. Inner Planets: Earth • Hydrosphere • Thick enough atmosphere to protect from UV • Mercury’s is too thin, no protection • Venus’ is too thick, traps energy • Oxygenated via volcanic gases & photosynthesis

12. Inner Planets: Mars Mars Rover Landing Surface Exploration Olympus Mons VallesMarinaris Polar CO2 “ice” caps Exobiology

13. Mars • Two tiny moons (20 km diameter) • Very thin atmosphere of carbon dioxide • No liquid water on surface • Mostly frigid (200 K), but occasionally warm (290 K) • Chance of microbial life, especially in past

14. Hrad Auqakuh Al-Qahira Maíadim Harmakhis MARS Huo Hsing Shalbatnu The Red Planet Her Descher Bahram Ares

15. WHY DO YOU THINK MARS IS RED? • Mars is red because that is where men are from. Men get red when they are angry or embarrassed or trying to not pass gas in mixed company.

16. WHY DO YOU THINK MARS IS RED? (b) Mars is red because it has such a thin atmosphere, which cannot hold the blue like the earth's atmosphere can. Mars is also red because of all of the rusted iron dust surrounding the planet and all the rusted iron on the planet.

17. WHY DO YOU THINK MARS IS RED? (c) The ancient Roman god, Mars, was a great hunter (and resident of Georgia) who was smeared with red blood. Mars had a gun rack on the back of his truck, and liked to shoot off his guns on New Year's Eve. Mars was originally called the Redneck god, but over time, people just started saying, "Mars is red."http://www.why-is-the-sky-blue.tv/mars-red.htm

18. OKAY, REALLY . . . • FROM http://image.gsfc.nasa.gov/poetry/ask/a10510.html • Mars’ is red because of the prevalence of iron oxides (rust) on the surface.

19. SCHIAPARELLI

20. H. G. WELLS • Lowell's theories influenced the young English writer H.G. Wells, who in 1898 published “The War of the Worlds” • In this novel, Wells created an invasion of Earth by deadly aliens from Mars and launched a whole new genre of alien science fiction. • Radio broadcast Halloween 1938

21. Mars landings (1976, 1997)

22. Why haven’t we gone to Mars? • 140 times farther than the moon (at best) • Months of weightlessness is crippling • Serious radiation hazards • Would have to carry food, fuel, oxygen to last years • Taking earth bacteria to Mars could confuse search for native Martian life • So much to learn from robotic exploration!

23. IS THE FACE ON MARS REAL? •  The "face" is nothing more than a hill that has been eroded by billions of years of Martian winds. The original Viking orbiter image showed the hill illuminated from an angle that highlighted certain features, creating the impression of a face.

24. WATER, VOLCANOES, ICE CAPS • Canyon: would reach from Chicago to LA if on Earth http://www.kidscosmos.org/kid-stuff/mars-facts.html • Dust storms can last for months • Two moons, Phobos (fear) & Deimos (panic)

25. VOLCANOES • Olympus Mons, largest volcano in the solar system • Covers an area about the size of Arizona • More than 3 times the height of Mt. Everest

26. Asteroids • “Asteroid” means “starlike” • Also called minor planets • 3 to 700 km diameter • Hundreds of thousands have been identified • The largest (Ceres) has a diameter of 1023 km • Most in belt between Mars and Jupiter • Some cross Earth’s orbit (called Apollo objects)

27. Source: http://www.solstation.com/stars/asteroid.htm Source: http://www.mira.org/fts0/planets/098/images/gaspra.jpg

28. Orbit of Mars Orbit of Earth Green dots represent minor planets Orbit of Jupiter Asteroid Belt (10/4/04) Source: http://cfa-www.harvard.edu/iau/lists/InnerPlot.html

29. Outer Planets: Overview • Outside asteroid belt • “Jovian” planets, or gas giants • Primarily hydrogen & helium • Low densities • Deep atmospheres • Rings • Many Satellites

30. Outer Planets: Jupiter • Largest planet in solar system • Could hold 1300 Earths • If 80x larger, would have become a star • 10-hour day • 12 (Earth)years to orbit sun • Great Red Spot: hurricane • Galilean Satellites • Io, Europa, Callisto, Ganymede

31. Jupiter • 11 times earth’s diameter (1/10 sun’s diameter) • 300 times earth’s mass (1/1000 sun’s mass) • Visible surface is gas (mostly hydrogen); interior must be mostly liquid, with solid core • Fascinating banded patterns, hurricanes, great red spot • Four large moons, many small ones • Visited briefly 4 times in 1970’s (Pioneer, Voyager); orbited by Galileo spacecraft 1995-2003

32. Saturn • Prettiest planet in small telescopes • 9 times earth’s diameter • 100 times earth’s mass (1/3 Jupiter) • Gaseous surface, liquid interior, solid core (like Jupiter) • Rings! • Many moons • Visited by Pioneer 11 (1979), Voyager 1 & 2 (1980-81); Cassini will arrive next year for a 4-year mission

33. Saturn’s rings Rings are mostly ice particles, from tiny grains to boulder-sized chunks. Gaps are created by tug of nearby moons.

34. Uranus • Discovered by William Herschel, 1781 • At the threshold of naked-eye visibility • Less than half the size of Saturn, and nearly twice as far • Another gas giant planet with rings (faint), many moons • Spin axis is tipped sideways • Visited by Voyager 2, 1986

35. Uranus • Discovered by William Herschel, 1781 • At the threshold of naked-eye visibility • Less than half the size of Saturn, and nearly twice as far • Another gas giant planet with rings (faint), many moons • Spin axis is tipped sideways • Visited by Voyager 2, 1986

36. Moons of Uranus All are icy, smaller than our own moon.

37. Neptune • Discovered by mathematics (anomaly in orbit of Uranus) in 1845-46, by John C. Adams and Urbain Leverrier • Can be seen in binoculars (looks like a faint star) • About the same size as Uranus, but 60% farther away • Voyager 2 discovered a cool blue spot, which has since disappeared • Largest moon, Triton, is a little smaller than our own and orbits backwards; surface is covered with ice

38. In a class by itself: Pluto • Is it a planet? (Neil DeGrasse Tyson on The Daily Show) • Small, rocky • Unlike other outer planets • Moon, Charon • Proportionally larger than the moons of any other planets • Discovered by Kansan in 1930 • Clyde Tombaugh, age 24 • Of Burdett, KS • While a teen, built his own telescopes, grinding his own mirrors • Asked advice from Lowell Observatory; was offered a job • Picture & narration

39. The comets • “Comet” means “hairy” • Thousands have been identified but the total population may be 10 trillion • Total mass may be greater than Jupiter’s • Divided into short-period and long-period comets • Located in two areas: • Kuiper belt • Oort cloud Source: http://www.solarviews.com/raw/comet/west.gif Source: http://www.solarviews.com/browse/comet/halebop2.jpg

40. Where the comets live Source: http://www.solarviews.com/browse/comet/kuiper3.jpg

41. The Oort cloud Source: http://spaceguard.esa.int/NScience/neo/neo-what/com-oort.htm