1. Section 4 – pg 562 The Outer Planets
Chapter 14
Section 4 – pg 562
The Outer Planets

2. Jupiter is so large that more than 1,300 Earths could fit within it
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Jupiter is so large that more than 1,300 Earths could fit within it
Jupiter has no solid surface

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Gas Giants and Pluto
The four outer planets – Jupiter, Saturn, Uranus, and Neptune – are much larger and more massive than Earth, and they do not have solid surfaces
Often called “gas giants”

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Like the sun, the gas giants have atmospheres composed mainly of hydrogen and helium
Due to their size, they have a lot of gravity which keeps the gas from escaping into space
This also causes them to have thick atmospheres
Also, most of the helium and
hydrogen is actually in liquid form
due to the pressure inside
the planet

15. All gas giants have many moons and is surrounded by a set of rings
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All gas giants have many moons and is surrounded by a set of rings
Ring: a thin disk of small particles of ice and rock

16. Jupiter Jupiter is the largest and most massive planet Pg 564
2.5 times the size of all the other planets combined

18. Jupiter’s Atmosphere Pg 564
Thick atmosphere made mainly of hydrogen and helium
Great Red Spot: a storm that is larger than Earth that doesn’t seem like it will ever stop
Jupiter has no land to slow down the storm, like Erath does
Swirling winds similar to a hurricane

19. Jupiter’s Structure Pg 564
We think that Jupiter has a dense core of rock and iron at its center
A thick mantle of liquid hydrogen and helium surrounds this core
The pressure at Jupiter’s core is about 30 million times greater than the pressure at Earth’s surface

20. Jupiter’s Moons Galileo discovered Jupiter’s four largest moons Pg 564
Io, Europa, Ganymede, and Callisto
We continue to discover new
moons using improved technology
Jupiter has more than 63 moons

21. Saturn The 2nd largest planet Thick atmosphere of hydrogen and helium
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Saturn
The 2nd largest planet
Thick atmosphere of hydrogen and helium
Atmosphere contains clouds and storms
Only planets whose average density is less than that of water

22. Saturn's Rings Saturn has the most spectacular rings of any planet
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Saturn's Rings
Saturn has the most spectacular rings of any planet
Made of chunks of rock and ice, each traveling in an orbit around the planet
Voyager discovered that the rings are divided into many thinner rings

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Saturn’s Moons
Saturn’s largest moon, Titan, is larger than the planet Mercury
Discovered in 1665, but we did not know what it was until Voyager flew by
Titan has such a thick atmosphere that little light can pass through it
Titan’s layers

25. Saturn has over 47 moons

26. Uranus Pg 567 4 times the size of Earth
Twice as far from the sun as Saturn, making it much colder

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Looks blue-green due to traces of methane in its atmosphere
Surrounded by a group of thin, flat rings

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Discovery of Uranus
In 1781, William Herschel found a fuzzy object in the sky that did not look like a star
Thought it might be a comet, but turns out to be a planet
Discovery made Herschel famous and started an era of active solar system study

29. Exploring Uranus About 200 years after it is
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Exploring Uranus
About 200 years after it is
discovered, Voyager 2 took
pictures of Uranus
Showed Uranus had a few
clouds and that Uranus
rotates in about 17 hours
Uranus’s axis of rotation is tilted at an angle of about 90 degrees from the vertical
Astronomers think that billions of years
ago something hit Uranus and knocked it
on its side

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Uranus’s Moons
Photos from Voyager 2 shows that Uranus’s five largest moons have icy, cratered surfaces
Uranus’s moons also have lava flows on their surfaces, suggesting that material has erupted from inside each moon
So far we have discovered 27 moons around Uranus

31. Neptune Pg 568 Neptune is a cold, blue planet
Atmosphere contains visible clouds
Scientists think that Neptune is slowly shrinking, causing its interior to heat up
As this energy rises toward Neptune’s surface, it produces clouds and storms in the atmosphere

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Discovery of Neptune
Astronomers discovered that Uranus was not following the orbit predicted for it
They hypothesized that the gravity of another, unseen planet was affecting Uranus’s orbit
They calculated the orbit of the unseen planet and soon discovered Neptune

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Exploring Neptune
In 1989, Voyager 2 photographed a Great Dark Spot on Neptune about the size of Earth
This was probably a storm like the one of Jupiter, however, the storm did not last
Many other storms and started and stopped since then

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Neptune’s Moons
We have discovered at least 13 moons orbiting Neptune
Largest moon is Triton, which has a thin atmosphere and has nitrogen ice at its south pole

35. Comparison of the planet’s moons

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Pluto
Pluto has a solid surface and is much smaller and denser than the outer planets
Made of a mixture of rock and ice
Pluto is smaller than Earth’s moon
Pluto has three known moons
The largest, Charon, is more than
half of Pluto’s size

37. Pluto’s Orbit Pluto takes 248 Earth years to revolve around the sun
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Pluto’s Orbit
Pluto takes 248 Earth years to revolve around the sun
Pluto’s orbit is very elliptical, bringing it closer to the sun than Neptune for part of its orbit

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Dwarf Planets
In recent years astronomers discovered many icy objects beyond Neptune’s orbit
Some are very similar to Pluto in size and makeup
Astronomers decided to create a new class of objects called “dwarf planets”
Dwarf planet: round and orbits the sun, but has not cleared out the neighborhood around its orbit

39. Chapter 14 Section 4 Homework - Pg 569

40. 1A. How are the gas giants similar to one another?

41. 1B. Why do all of the gas giants have thick atmospheres?

42. 1C. List the outer planets in order of size, from smallest to largest

43. 1D. Compare the structure of a typical terrestrial planet to that of a gas giant

44. 2A. Describe an important characteristic of each planet that helps to distinguish it from the other outer planets

45. 2B. How is Pluto different from the gas giants?

46. 2C. Why did astronomers reclassify Pluto as a dwarf planet?