1. Chapter 27 – The Planets and the Solar System Page 586 Do you think it is possible to count the rings of Saturn? The rings look solid in the image, do you think they are? What do you think they are made of? What do we know about the planets?

2. Chapter 27.1

3. The Inner Planets

4. Two Planetary Neighborhoods Inner Planets – Mercury, Venus, Earth, Mars All have rocky crust Dense mantle layers and cores Because of their Earth like appearance they are also known as terrestrial planets

5. Distance Between Planets Outer Planets – Jupiter, Saturn, Uranus, Neptune and Pluto 1 st four are called Jovian – or Jupiter like Very large gaseous planets with no rocky crust Low density due to size Have ring systems Pluto is an oddball – not dense enough to be terrestrial; too small to be Jovian

6. Mercury Nearest to the Sun Orbits the sun in 88 days Smallest of terrestrials Mercury surface resembles the moon’s Rotates every 59 days Temperature – day 400°C; night – 200°C

7. Chapter 27.2

8. Venus – Earth’s Sister Planet – 2 nd planet from the Sun Near each other similar in diameter, mass and gravity Venus is the only planet to rotate from east to west Rotates every 243 days Orbits every 225 days Thick yellow clouds make surface impossible to see

9. Magellan radar mapped it Fault system Yellow clouds made of sulfuric acid Surface is hot due to greenhouse effect (CO 2 ) causing surface to be 475°C Visible from Earth in the morning or early evening – “evening star”

10. Mars – 4 th planet from the Sun 687 day orbit Axis tilted about the same as earth’s giving it seasons. However they are 2 times as long Very thin atmosphere (1% of Earth’s) mostly CO 2 Has ice caps – thought to be water covered by frozen CO 2

11. Spacecraft have photographed and landed on Mars surface Largest known volcano in the solar system “Olympus Mons” Has a valley system suggesting water once ran on its surface Page 543, 5 Martian landings

12. Outer Planets

13. Jovian Planets – Jupiter, Saturn, Uranus and Neptune Much larger than terrestrials – smallest, Uranus, is 15 times more massive than earth No solid surfaces – their “surface” is an uppermost gas layer Composed mainly of light elements H and He All Jovian planets have ring systems

14. Jupiter – 5 th Planet from the Sun 11.9 year orbit 10 hour rotation Has 2 times more mass than all the other planets combined Radiates 2 times as much energy back into space as it receives from the sun Galileo probe entered Jupiter’s atmosphere in 1995 – found no thick clouds and higher than expected temperatures

15. Saturn – 6 th planet from the Sun 30 year orbit 10 hour rotation Lowest density of all planets, less than 1 Saturn also radiates more energy than it receives from the sun, like Jupiter it has internal heat sources

16. Uranus – 7 th planet from the sun 84 year orbit 17.2 hour rotation It’s rotational axis is tipped almost completely over It’s magnetic field is not tipped

17. Chapter 27.3

18. Neptune – 8 th planet (most of the time) 165 year orbit Rotation 16.1 hours Neptune was found after astronomers predicted its location mathematically in 1846 Winds over 2000 km/hr Becomes the 9 th planet when Pluto is taken close to the Sun due to Pluto’s highly elliptical orbit

19. Pluto 248 year orbit Smallest planet in the Solar System Its moon, Charon, is ½ its size Most of its atmosphere is frozen. However, it thaws slightly when it nears the sun

20. Planetary Satellites (moons)

21. Satellites of Earth and Mars Earth has one moon Mars has 2 tiny moons, Deimos and Phobos Phobos circles mars 3 times a day Mercury and Venus have no satellites

26. Jupiter’s Moons At least 63 Galilean moons – Io, Europa, Ganymede and Callisto are the 4 largest discovered by Galileo

28. Io is geologically active Nine active volcanoes No signs of crater impacts Galileo spacecraft found it has an iron core surrounded by a molten silicate rock Heat on Io is caused by tidal forces from Jupiter

30. Europa Surface is thought to be frozen water It is thought liquid water may exist under the ice

32. Ganymede – the largest Larger than Pluto and Mercury Surface of ice Callisto – most heavily cratered object in the solar system

35. Saturn’s Moons At least 31 moons Largest is Titan Only moon in solar system to have a substantial atmosphere

38. Uranus’s Moons At least 27 5 major moons are Titania, Oberon, Umbriel, Ariel, and Miranda All lack atmosphere and are heavily cratered

41. Neptune’s Moons At least 13 moons – Triton is the largest

44. Solar System Debris

45. Comets and TNOs (Trans Neptune Objects) Comets described as dirty snowballs Spend most of their time beyond the orbit of Neptune Do not become visible until they travel inside Jupiter’s orbit

46. Has 2 parts, nucleus and tail Tail always points away from the sun due to solar winds Most famous comet is Halley’s, it appears once every 76 years – last visit 1986

47. Asteroids – solid rocklike masses Uneven surface causes their brightness to change Revolve same direction as planets Most in asteroid belt between Mars and Jupiter

48. Meteors and Meteoroids Meteoroid – rock or ice fragment traveling in space, they differ from asteroids in that they are smaller in size Meteor – when a meteoroid enters earth’s atmosphere and burns up “shooting star”

49. Meteor shower – occurs when earth passes into debris left by a comet that crossed earth’s path – very predictable, named after the constellation in the background.

50. Chapter 27.4

51. Meteorite A large meteoroid that survives earth’s atmosphere and strikes its surface 3 types Stony – resemble earth’s rocks, mostly made of silicates 95% Irons – mostly iron 5% Stony irons <1% Most found in the ice of Antarctica

52. Impact Craters – bowl shaped depressions that remain after a meteor or other object strikes earth Rare on earth because The atmosphere burns up most meteoroids Earth is geologically active Best known is Barringer Meteor Crater in AZ