Transcript Moons in our Solar System

The Moons of
Our Solar System
How many moons are in our solar system?
1? 9? 61? 159?
159 and counting!
Moons of the Inner Planets
Mercury = 0
Venus = 0
Earth = 1, The Moon
Mars = 2, Phobos & Deimos
Moons of the Outer Planets
Jupiter = 63, including Callisto, Io, Europa, Ganymede
Saturn = 56, including Titan, Enceladus, Dione, Pan
Uranus = 27, including Ariel, Titania, Puck, Oberon
Neptune = 13, including Triton, Galatea, Larissa
Pluto = 3, Charon, Nix, Hydra
Comparing the Moons with Earth
The Earth’s Moon
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384,403 km (238,857 mi) from
Earth & 3,476 km (2,160 mi) in
diameter
27 days, 7 hours, 43 minutes
for rotation and revolution
around the Earth
Earth’s gravity keeps the same
face of the moon permanently
turned toward us
The Earth’s Moon
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It’s the only other place in the Solar System
that humans have visited.
Recently, water ice was discovered at the
poles underneath the dusty, cratered surface
A “blue moon” is a second full moon in 1
month, & occurs every few years
The Earth’s Moon
along with Jupiter &
4 of its moons
The Moons of Mars
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Mars has 2 moons: Phobos & Deimos
In Greek, Phobos means “fear” & Deimos means
“dread”; they are the sons of Mars, the god of
war
These moons are heavily cratered & probably
captured objects
The Moons of Mars
Phobos is 27 km (17 mi) wide and
completes its orbit of Mars in 8 hours
 Deimos, at 14 km (9 mi), is one of the
smallest moons in the Solar System
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Phobos
Deimos
The Moons of Jupiter
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Jupiter has 63 moons & thousands of small
objects orbiting it
Scientists refer to it as a “mini Solar System”
Jupiter with its moon, Io
The Moons of Jupiter
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In 1610, Galileo was the first person to
discover the largest moons of Jupiter:
Ganymede, Callisto, Io, and Europa
Since then, several spacecraft have
examined these “Galilean Satellites” closely
Ganymede
Callisto
Io
Europa
The Moons of Saturn
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Saturn has 56 moons
The Cassini spacecraft discovered 12 new
moons orbiting the planet in 2005 alone
Saturn
Cassini spacecraft
The Moons of Saturn
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Saturn’s moons vary greatly in size & shape
Titan, the largest moon, contains ingredients
that one day may nurture life!
The Moons of Uranus
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Uranus has 27 moons
Many of them are icy, without an atmosphere
or magnetosphere
The rings of Uranus and its
many moons
The Moons of Uranus
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The 5 largest were discovered in the
19th and 20th centuries: Titania, Oberon,
Umbriel, Ariel & Miranda
Titania
Oberon
Umbriel
Ariel
(images not to scale)
Miranda
The Moons of Neptune
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Neptune has 13 moons, 3 of which were
discovered in 2002, 2 more in 2003
In 1989, Voyager 2 discovered 6 moons not
visible from Earth
All of Neptune’s
moons are
composed of rock
& ice, but little
else is known
about them
The Moons of Neptune
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Neptune has 3 larger moons: Triton, Nereid &
Proteus
Triton is the only moon in the solar system with
a retrograde orbit, and 1 of 3 with an atmosphere
Nereid
Proteus
Images from Voyager 2 in 1989
Triton
The Moons of Pluto
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Pluto has 3 moons: Charon, Nix, and Hydra
Charon and Pluto have a mutually
synchronous orbit, meaning they always
show the same face to each other
For the Greeks, Charon was the boatman
who carried dead souls to the underworld,
ruled by Pluto
Pluto
Charon
The Moons of Pluto
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At 1,186 km (737 mi), Charon’s diameter is
little more than half of Pluto’s; no other
moon in our solar system is so close in
size to its planet
Charon appears to be covered by water
ice, differing from Pluto’s surface of
frozen nitrogen, methane & carbon
dioxide
Hubble Space
Telescope image of
Pluto (left) & Charon
The Moons of Pluto
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In November 2005, astronomers discovered two new
moons of Pluto: Nix and Hydra. Both moons are
much farther away from Pluto than Charon, and
many times smaller.
Nix is named after the Greek goddess of night,
Charon’s mother. Hydra is a beast that guarded
Pluto’s underworld.
Moons of Our Solar System
Earth is not the only planet with a moon. At least
159 moons with craters, volcanoes & other
spectacular features exist in our solar system.
Which ones are your favorites?