AST301_Lecture14.pdf - AST301 Lecture 14 Chapter 12 RINGS,...

AST301 Lecture 14
Chapter 12 RINGS, MOONS, AND PLUTO

AST301 Lecture 14
Chapter 12 RINGS, MOONS, AND PLUTO
Learning Goals:
At the end of this lecture you will:
Ø Know more about the major moons of Jupiter
Ø Understand the concept of tidal heating
Ø Know more about Saturn’s major moons
Ø Know more about Pluto and the Kuiper belt
Ø Understand the ring systems of the giant planets

AST301 Lecture 14 Chapter 12 RINGS, MOONS, AND PLUTO

AST301 Lecture 14 Chapter 12 RINGS, MOONS, AND PLUTO
The Galilean Satellites (Jupiter):

• The colors are caused by sulfur
and its compounds.
• The dark spots are volcanoes.
• The volcanoes are active today.
Their lava is rich in sulfur and
sulfur compounds.
• Superhot volcanoes
• Youngest surface in Solar System
• Most volcanic object in Solar
System!
Jupiter’s Moon Io
AST301 Lecture 14 Chapter 12 RINGS, MOONS, AND PLUTO

Europa: second moon out from Jupiter
• Europa is entirely covered by water ice.
• The ice layer is several kilometers thick.
Ice in Europa (up) vs. Earth (down)
AST301 Lecture 14 Chapter 12 RINGS, MOONS, AND PLUTO

AST301 Lecture 14 Chapter 12 RINGS, MOONS, AND PLUTO
Ice surface
• The layer of salt
water (not ice) is
inferred from the
electrical and
magnetic properties
of Europa.
• As free-flowing
water is a
requirement for life,
it has been
suggested that life
might exist on
Europa.
Both, Europa’s and Io’s
interiors are getting
heated! BUT HOW?
Europa has salt water ocean below its ice surface

Jupiter’s gravity raises tides in its moons
• The varying distortion causes
friction inside the moons.
• The friction heats the moons.
• Io is closest to Jupiter and has the shortest orbital period (1.8 days), so it is heated most.
• Callisto is furthest from Jupiter and has the longest orbital period (16.7 days), so it is
heated least.
• Io is heated so much that it has continuous volcanic activity. Its surface is replaced every
few million years. It has become even more differentiated than the Earth, and sulfur has
floated to its surface.