Chapter 27 – The Planets and the Solar System

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 • 1st 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 – 2nd 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 (CO2) causing surface to be 475°C • Visible from Earth in the morning or early evening – “evening star”

10. Mars – 4th 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 CO2 • Has ice caps – thought to be water covered by frozen CO2

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 – 5th 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 – 6th 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 – 7th 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 – 8th 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 9th 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

22. Earth

23. Moon

24. Mars

25. Phobos

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

27. Jupiter

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

29. Io

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

31. Europa

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

33. Ganymede

34. Callisto

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

36. Saturn

37. Titan

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

39. Uranus

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

42. Neptune

43. Triton

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