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Astronomy The Planets and Their Moons

Solar System Formation Nebular Hypothesis: Video Summary

The Planets Solar System to Scale in size AND distance!

Planet Groupings Divided by the asteroid belt! The Inner Planets “Terrestrial” – Mercury – Venus – Earth – Mars The Outer Planets “Jovian” – Jupiter – Saturn – Uranus – Neptune The Dwarf Planets

Inner Planets vs. Outer Planets The Inner Planets: – Rocky crusts – Dense mantle layers – Very dense cores The Outer Planets: – Gaseous atmospheres (outer layer mostly made of hydrogen) – a lower density than Earth – ring systems inside their moons – large compared to Earth Pluto

5 Dwarf Planets 1. Eris (KBO) 2. Pluto (KBO) 3. Haumea (KBO) 4. Makemake (KBO) 5. Ceres (Asteroid Belt)

Dwarf Planet Characteristics

As of Summer, 2006… 3 Primary Dwarf Planets: – Ceres (Asteroid Belt) Discovered in 1801 –At first, called a planet, then “demoted” when other asteroids discovered 2015: Dawn Mission – Pluto (Kupier Belt) Discovered in 1930 by Clyde Tombaugh –In 2006, reclassified as a Dwarf Planet 2015: New Horizons Mission – Eris (Kupier Belt) Discovered in 2003 Has 1 moon Bigger than Pluto; VERY far out from the Sun!

The Inner Planets Mercury Video1-Messenger Crash Video2 Video1 Video – no atmosphere – EXTREME temperatures Venus – no magnetic field – atmosphere of CO 2 and sulfuric acid – temps near 475 C (all that CO 2 !) – atmospheric pressure is 90 times greater than on Earth (CO 2 is more dense than N 2 and O 2 ) Earth – Water and oxygen Mars – very thin atmosphere – 95 % CO 2, 5% N and Ar – polar ice caps of frozen water and CO 2 – dust storms = atmosphere – Largest volcano in Solar System: Olympus Mons

Venus and Mercury: Phases! Why?

Transits Transits – when one planet (or moon) crosses in front of the Sun (or its planet) and shows up as a shadow. Transits seen from Earth – Mercury and VenusVenus – Why? Which 2 planets are between us and the Sun? Transit of Venus: June 8, 2004

The Jovian (outer) Planets Jupiter – strongest magnetic field of all planets – gasses appear as bands – spots appear and disappear – radiates heat Saturn – fairly strong magnetic field – fewer gaseous bands – radiates heat Uranus – avg. temp is –200 C – methane gas is atmosphere – rotates on its side but magnetic field is not tipped Neptune – winds around 2000 km/hr – temps around –225 C – atmosphere is 74% hydrogen, 25% helium, 1 % methane

Neptune’s Orbit and Pluto Neptune is sometimes the farthest out planet! – Neptune and Pluto’s orbits cross each other – Will they ever collide? NO!NO! Pluto – 70% rock, 30% water – temps from –235 C to –210 C – moon Charon is about ½ the size of the planet (1 of 5 moons!) – (first color photo from New Horizons space craft!)

Planet Chart Comparison* *This is in your textbook - # moons is VERY out of date! PlanetDist- ance To Sun RevolutionRotationDiameterMass (Earth = 1) Dens- ity # (major) Moons Mercury d.59 d.4, Venus d.243 d.12, Earth d.24 h12, Mars d.24 h 37 m6, Jupiter y.9 h 50 m142, Saturn1, y.10 h 14 m120, Uranus2, y17 h 14 m51, Neptune 4, y16 h49, Pluto5, y6 d 9 h2,

Largest Moons and Smallest Planets

Martian Moons Phobos and Deimos – small and irregularly shaped – Thought to have been captured asteroids (from the nearby asteroid belt that runs between Mars and Jupiter) – Phobos will crash to the surface in about 50 million years

Jupiter’s Moons Jupiter has at least 28 moons Four largest (Galilean) – Io: active volcanoes; thin atmosphere – Europa: atmosphere; layer of ice – Ganymede: largest moon in the solar system; magnetic field – Callisto: some oxygen in atmosphere

Telescope View of Galilean Moons

Jupiter’s Moon’s Features

Saturn’s Moons and Rings Saturn has at least 24 moons – Titan – half rock, half frozen water; atmosphere Rings are made of mostly water ice and some dust

Saturn’s Satellites and Ring Structure

Uranus’, Neptune’s and Pluto’s Moons Uranus: at least 21 moons – Titania, Oberon, Umbriel, Ariel, Miranda – None have atmospheres and many impact craters Neptune: 8 moons – Triton close to the size of Earth’s moon southern ice cap made of methane and ammonia ice volcanoes (??) very thin atmosphere Orbits backwards! Pluto: Charon (and 3 smaller – Nix, Hydra, Kerberos) Pluto – About ½ the size of Pluto – Really, they orbit each other!

Venus and Mercury: Phases! Why?

Transits Transits – when one planet (or moon) crosses in front of the Sun (or its planet) and shows up as a shadow. Transits seen from Earth – Mercury and Venus linklink – Why? Which 2 planets are between us and the Sun? Transit of Venus: June 8, 2004

With the rest of class… 1. Finish the questions in the notes (Q 1-30) – We’ll go over any you can’t find during the last 10 mins of class today 2. Pick up the test review – The front side will be collected/graded next class – The back side is a study guide for the test 3. Work on your 3x5 index card “cheat sheet” – It will be collected after the test (not graded)

Q’s? 5. The Moon 6. The Sun burned it off 7. CO2 in atmosphere (Greenhouse gas) makes it over 900F. Atmosphere’s pressure is 90x Earth’s. No magnetic field. Rains sulfuric acid. 8. Venus hour day/night cycle, semi-habitable temperature range, presence of water

Q’s? 10. Yes! Gas atmosphere, liquid layer, small solid core. 11. It’s too small to be a star. 12. Jupiter & Neptune 13. It’s less dense than water 14. Methane 15. Uranus 16. A giant collision knocked it over

Q’s ? 17. It hasn’t cleared other objects from its orbit. 18. Kuiper Belt Objects

Q’s? 19. Mercury & Venus 20. Asteroids 21. They’ll crash to the surface of Mars 22. It’s right next to the asteroid belt 23. Io, Europa, Callisto, Ganymede 24. Rock and water ice 25. There are many impact craters & fractures 26. Ganymede (Jupiter) & Titan (Saturn) 27. It’s very far from the Sun so it doesn’t reflect much light

Q’s? 28. When a planet passes in front of the Sun or a moon passes in front of its planet 29. Mercury & Venus 30. They’re the only two between Earth and the Sun.

Review: Planets and Moons 1. What divides the inner and outer planets? 2. What characterizes the terrestrial planets? 3. What characterizes the Jovian planets? 4. Why couldn’t we live on our “sister planet”? FOUR REASONS! 5. Which 2 planets radiate more heat than they receive? 6. Which planet is tipped on its side? 7. Which “planets” occasionally flip-flop positions in the solar system? 8. Using your planet-chart comparison, answer these questions: a. Which planet has the fastest rotation AND the largest size? b. Which planets have a smaller mass than the Earth? c. Which planet has a density less than water? (less than 1) 9. Which 2 moons are bigger than Mercury? Which planets do they belong to? 10. What are the names of the Galilean moons? 11. What are Saturn’s rings made from? 12. Which two planets could we see cross in front of the Sun? Why not other planets?