Transcript Chapter 30 - Cloudfront.net

Chapter 30, Section 4
30.4 Satellites of Other Planets
Introduction
Until the 1600s, astronomers thought that
Earth was the only planet with a moon.
 In 1610, Galileo discovered moons orbiting
Jupiter.
 All planets in our solar system have
moons, except Mercury and Venus.
 Jupiter, Saturn, Neptune, and Uranus
have rings.

Questions

Which planets have moons?


Earth, Mars, Jupiter, Saturn, Uranus, Neptune
Which planets have rings?

Jupiter, Saturn, Neptune, and Uranus
Moons of Mars - Phobos
Phobos orbits Mars in 7 hours 40 minutes
 27km at widest, 19km at shortest point.
 Many craters, one is 8km across.
 Not spherical.

Moons of Mars - Deimos
Deimos orbits Mars in about 30 hours
 15km at widest, 11km at shortest point
 Many craters

What
does a large
number of craters
suggest about the age
of Phobos and
Deimos?
Question

Name the two moons of Mars?

Phobos and Deimos
Ring and Moons of Jupiter
 Galilean moon any one of the four largest satellites of
Jupiter—Io, Europa, Ganymede, and Callisto - that were
discovered by Galileo in 1610
 In addition to the four large moons discovered by
Galileo, scientists have observed dozens of smaller
moons around Jupiter.
 Of Jupiter’s four Galilean moons, three are larger than
Earth’s moon.
 Jupiter has a single, thin ring made of microscopic
particles that may have been given off by Io.
Rings and Moons of Saturn
 Saturn has over 30 moons, but only five moons
are fairly large.
 Saturn’s largest moon is Titan, which has a
diameter of over 5,000 km.
 Saturn’s set of rings was discovered over 300
years ago. Each of the rings circling Saturn is
divided into hundreds of small ringlets, which are
then composed of billions of pieces of rock and
ice.
Question

What are the names of the four moons of
Jupiter discovered by Galileo?


How many are bigger than earth?


Io, Europa, Ganymede, and Callisto
Three
What is the name of Saturn’s largest
moon?

Titan
Satellites of Uranus
Uranus’s four largest moons, Oberon,
Titania, Umbriel, and Ariel, were known by
the mid-1800’s.
A fifth moon, Miranda, was discovered in
1948. Scientists now know that Uranus
has over two dozen moons.
Uranus also has a dozen thin rings.
Satellites of Neptune
Neptune has at least eight moons. One of
these moons, Triton, revolves around
Neptune in a retrograde orbit.
Neptune’s relatively small number of rings
are clumpy rather than thin and uniform.
Satellites of Pluto
 The relationship between Pluto and its moon
Charon is unusual because Charon is almost
half the size of Pluto itself.
 Because Pluto and Charon are similar in size,
some scientists consider them to be a doubleplanet system.
 Charon completes one orbit around Pluto in 6.4
days, the same length of time as a day on Pluto.
Because of these equal lengths, Charon stays in
the same place in Pluto’s sky.
Questions

What are the names of Uranus’s four
largest moons?


How many moons does Neptune have?


Uranus’s four largest moons are Oberon, Titania,
Umbriel, and Ariel
At least 8
What is interesting between Pluto and
Charon?

Because Pluto and Charon are similar in size, some
scientists consider them to be a double-planet
system.