to the Solar System

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to the Solar System
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Travel Guide

• Welcome to our tour of the solar system. Were
  going to visit the Sun, all 9 planets in the
  solar system, and even do a little sightseeing
  along the way. Make sure youve got film in your
  camera and a comfortable seat. Lets go!

We Start at The Sun
Skip to the Inner Planets
Skip to the Outer Planets
Skip to The Sights
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The Sun

• Did your mother ever tell you not everything
  revolves around you? She was right! Everything
  in our solar system revolves around the sun.
  
• So grab your 2000 SPF sun block and your darkest
  sunglasses. Our first stop is The Sun.
  
• The ancient Greeks thought the Sun was a god
  called Helios that drove a horse and chariot
  across the sky. The Romans called him Sol.

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The Sun
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• Our Sun is a G2 star and is just one of more than
  100 billion stars in our galaxy
  
• Our Sun is the biggest object in our solar
  system it makes up 99.8 of the total mass
  
• Currently the Sun is made up of about 75
  hydrogen and 25 helium. This changes over time
  as the Sun converts hydrogen to helium in its
  core through nuclear fusion
• Scientists believe the Sun is about 4.5 billion
  years old
  
• Core temperature is estimated to be 15,000,000
  C
  
• The Sun travels too! The time it takes to
  revolve around the galaxy is about 250 million
  Earth years
  

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Inner Planets

• The asteroid belt between Mars and Jupiter
  separates the Inner Planets and the Outer
  Planets
  
• The Inner Planets are the first four closest to
  the Sun
  
• These planets are also called the rocky or
  terrestrial planets because theyre made up
  mostly of rock and metal
  
• They also have solid surfaces, a slow rotation,
  no rings, and they have few or no satellites like
  moons

We start at Mercury
Skip to Venus
Skip to Earth
Skip to Mars
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Mercury
Mercury is our first planetary stop, just 57.8
million km from the Sun. Because Mercury is so
tiny only Pluto is smaller than Mercury it
wont take long for our tour.

• Mercury is named after the Roman god hes
  called Hermes in Greek mythology. He was the god
  of commerce and thievery, and was the messenger
  of the gods with his winged sandals. Since
  Mercury moves so quickly across the sky, thats
  probably why this planet was named after this
  faster-than-lightning god.

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Mercury
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• Bundle up and bring shorts Mercurys
  temperatures are as high as 427 C on the side
  facing the sun and as low as -183 C on the side
  facing away from the sun
• The average surface temperature is 179 C
• Mercury is a lot like our Moon its very old
  and has lots of craters
  
• You can see Mercury with binoculars, but its
  always so close to the Sun that its hard to see
  
• Mercury has an atmosphere, but its very thin
• Mercury revolves around the Sun thats one year
  in 87.9 Earth days
  
• Mercury rotates in 58.6 Earth days its day is
  almost as long as its year!
  

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Venus

• Do you have a boyfriend or a girlfriend on this
  trip? If you do, youre lucky, because our next
  stop, just 50.3 million km from Mercury, is the
  planet of love!
• Even though its a planet, Venus is also called
  the evening star and the morning star because
  its the brightest star in the sky in the early
  evening and early morning.

Venus is named for the Roman goddess of love and
beauty. In ancient Greece, her name was
Aphrodite. The planet is probably named for
Venus because it is the brightest and most
beautiful planet in the sky.
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Venus
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• Venus is covered in dense clouds made up of
  sulfuric acid. These clouds keep the heat in, so
  even though its farther from the Sun, Venus is
  hotter than Mercury! This is called a
  greenhouse effect
• The average temperature on Venus is 482 C
• Unlike most planets, Venus rotates
  counterclockwise, so the Sun rises in the west
  and sets in the east. This is called retrograde
  motion
• Venus revolves around the sun in 224.7 Earth
  days
  
• Venus rotates on its axis in 243 Earth days so
  its day is longer than its year!

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Earth

• Did you forget your toothbrush? Dont worry,
  Earth is right on the way to our next planet, so
  well stop home for a quick layover before
  continuing our tour. Besides, its only 41.4
  million km from Venus, so it wont take long.
  Watch out for the Moon its the first one weve
  seen so far.

The Earth is the only one of the planets in our
solar system that isnt named for a Roman or
Greek god. The name comes from the Middle
English word eorthe meaning ground.
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Earth
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• Like the old TV show says, Earth is the 3rd rock
  (or planet) from the Sun only 152 million km
  away
  
• Unlike other planets, Earth is the only one with
  liquid water on the surface it covers about 70
  of the planet
  
• Our atmosphere is mostly nitrogen (78) and
  oxygen (21)
  
• Earth is also different from the other planets
  because its crust is divided into separate plates
  that float around on top of the mantle, called
  tectonics
• The average temperature on Earth is 15 C
• Earths revolution is exactly 365.26 days
• Earths day is exactly 23.93 hours long

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Mars

• Its going to take a little longer to get to our
  next planet. Mars is 78.3 million km from Earth,
  our biggest jump yet. Early science fiction
  writers wrote about aliens from Mars in their
  books and movies, but scientists have proven
  there is no life on Mars now. You can see Mars
  without a telescope from Earth.

Mars was named after the Roman god of war Ares,
to you Greeks probably because of its red
appearance. Mars is also sometimes called the
Red Planet for the same reason.
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Mars
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• Mars has permanent ice caps at both its north and
  south poles made up of water ice and solid carbon
  dioxide, that we call dry ice
  
• There is evidence of erosion on Mars, meaning
  that long ago there were rivers and floods of
  some kind of liquid, maybe water
  
• Youll want to bring lots of clothes when we
  visit Mars. The average temperature is -63 C,
  but it can range anywhere from -140 C to 20 C
  
• The atmosphere there is mostly carbon dioxide
• Mars has 2 moons, named Phobos and Deimos
• Some meteorites found on Earth are really broken
  off pieces of Mars
  
• Mars revolves around the Sun in 686.98 Earth
  days
  
• Its day is almost the same as ours 24.6 Earth
  hours
  

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Outer Planets

• The Outer Planets are made up of the gas or
  Jovian planets and Pluto
  
• The gas planets have low densities (meaning
  theyre less solid), fast rotations, deep
  atmospheres, rings, and lots of satellites or
  moons
• Pluto is a small rocky planet unlike the its
  neighboring gas planets
  
• Before we hit the Outer Planets, lets do a
  little sightseeing first!
  

Start Sightseeing
Skip to Jupiter
Skip to Saturn
Skip to Uranus
Skip to Neptune
Skip to Pluto
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Sightseeing

• While were making our way to the Outer Planets,
  you might want to take in some of the solar
  system tourist attractions
  
• Take a ride on a Comet
• Hurtle through space on an Asteroid
• Wish upon a falling Meteoroid

See the Sights
Skip to Jupiter
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Comets

• Comets are sometimes called dirty snowballs,
  because theyre a mixture of ices water ice and
  frozen gas ice and dust
  
• As of 1995, scientists had identified 184 comets
  with orbital periods less than 200 years
  
• Halleys Comet is one of these and we see it from
  Earth every 86 years
  
• Scientists believe something called the Oort
  Cloud exists in the outer reaches of the solar
  system and it may contain over a trillion comets
  
• Scientists also believe many short-period comets
  start out from the Kuiper Belt, an area past the
  orbit of Neptune

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Asteroids

• An asteroid is a rocky body that can be only a
  few hundred feet wide or several hundred miles
  wide.
  
• Scientists think asteroids are leftover particles
  from the time the solar system formed
  
• Lots of asteroids orbit the Sun in between Mars
  and Jupiter, an area that separates the Inner and
  Outer Planets
  
• Scientists think that Jupiters strong
  gravitational force keeps the asteroids in the
  belt and protects Mercury, Venus, Earth, and Mars
  from being bombarded by asteroids on the loose!

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Meteoroids

• A meteoroid is a piece of rocky or metallic
  debris, usually about the size of a small rock
  
• When a meteoroid enters the Earth's atmosphere,
  it gets so hot it glows and we can see it from
  Earths surface. Now its become a meteor, even
  though we call it a falling or shooting star
  and make a wish.
• When the Earth passes through an orbiting stream
  of debris from a comet that has broken up, we see
  a meteor shower, with lots of meteors burning up
  in the atmosphere
• If the meteor does not burn up completely, the
  remaining portion hits the Earth and is called a
  meteorite

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Jupiter

• It will take awhile to get to our next stop,
  since its 550.4 million km from Mars. But it
  will be worth it! Jupiter is biggest of the
  planets in our solar system if it were hollow,
  all the other planets could fit inside and there
  would still be room left over!
• You can see Jupiter from Earth without a
  telescope. Its the brightest planet in the sky,
  next to Venus (and sometimes Mars).
  

Jupiter, the biggest planet in the solar system,
was named after Jove, the Roman king of the gods
and ruler of Olympus. His Greek name is Zeus.
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Jupiter
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• We wont be taking any walking tours on Jupiter,
  since like all the gas planets, it doesnt have a
  solid surface to walk on. Most of the planet is
  made up of liquid metallic hydrogen
• Jupiter has rings, like Saturn, but theyre a lot
  smaller and fainter, which makes them impossible
  to see without a powerful telescope
  
• Jupiters atmosphere is mostly hydrogen (90) and
  helium (10)
  
• The average temperature of its clouds is -121 C
• Jupiter has a whopping 52 known satellites!
• Jupiter takes 11.78 Earth years to revolve around
  the Sun
  
• One day on Jupiter is only 9 Earth hours and 55
  minutes
  

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Saturn

• Weve got a long way to go about 648.6 million
  km to get to the 6th planet in the solar
  system, but make sure youve got your cameras
  ready for a spectacular sight. The rings of
  Saturn are known throughout the galaxy as a
  must-see.
• The rings are really made up of icy, rocky
  particles that range from a few centimeters to a
  few kilometers wide. They form rings by orbiting
  Saturn. Some of Saturns moons, called
  shepherding satellites keep the rings in place
  by their gravitational pull.

Saturn was named for the Roman god who was the
father of Jove/Jupiter his name was Cronus in
Greek mythology. He was also the god of
agriculture.
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Return to Travel Guide
Saturn

• Saturn is the second gas planet on our tour and
  has the lowest density of them all if you could
  put a planet in a bathtub, Saturn would float!
  
• Even though its not dense, its big! Only
  Jupiter is bigger than Saturn
  
• Saturn has 18 named satellites, plus another 12
  that are so new scientists havent named them
  yet
  
• Saturns atmosphere like Jupiters is mostly
  hydrogen (75) and helium (25). Also like
  Jupiter, the planet is mostly made up of liquid
  metallic hydrogen
• The average cloud temperature on Saturn is -125
  C
  
• Saturns revolution around sun takes 29.46 Earth
  years
  
• Rotating on its axis takes 10 Earth hours and 40
  minutes
  

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Uranus

• Hope you brought a good book with you, because
  weve got a ways to go to get to our 7th planet.
  From Saturn, Uranus is about 1.444 billion km
  away. If we were traveling straight from the
  Sun, wed have to go 2.87 billion km to get to
  Uranus.
• Uranus was discovered in 1781, so its
  considered the first planet discovered in modern
  times (even though 1781 is still pretty long
  ago).
• If you knew exactly where to look, you could
  probably see Uranus with binoculars from Earth
  

This is starting to look like a family tree. In
Greek mythology, Uranus is the father of Cronus
(Saturn to the Romans, and our last stop) and
grandfather of Zeus (also known as Jove or
Jupiter). Uranus was the first and oldest king
of the gods for the ancient Greeks.
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Uranus
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• Unlike Jupiter and Saturn, that are mostly liquid
  metallic hydrogen, Uranus is made up of mostly
  rock and ices
  
• The atmosphere of Uranus is mostly hydrogen (83)
  plus a little helium (15) and methane (2)
  
• The average cloud temperature is -193 C
• Like the other gas planets, Uranus has rings, but
  theyre dark, faint and made of up small up to
  10 meter particles. We know of 11 rings, but
  there might be more we just havent seen yet
• Uranus has 20 moons that are named and another
  newly discovered one that isnt named
  
• Uranus is different from all the other planets
  because its tilted on axis so that poles face
  towards the Sun
  
• One revolution around the Sun is 84.01 Earth
  years
  
• One rotation is only 17 Earth hours and 14
  minutes (have you noticed how fast these gas
  planets spin?)
  

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Neptune

• Our tour isnt over yet, but were getting
  really far from home. Neptune, the next stop on
  our whirlwind tour, is over 4.5 billion km from
  the Sun and over 4.3 billion km from Earth! This
  is the last gas planet on our tour of the Outer
  Planets.
• Neptune was discovered in 1846, which, like
  Uranus, is considered discovered in modern times.
  Like Uranus, if you know exactly where to look,
  you can probably see Neptune with binoculars from
  Earth.

Neptune is the Roman god of the sea hes called
Poseidon by the ancient Greeks. Neptune was
named for a sea god because of its bright blue
color, caused by the methane in its atmosphere.
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Neptune
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• Neptune is usually the 8th planet from the Sun,
  but occasionally Plutos orbit crosses Neptunes
  orbit, making Neptune the farthest from the Sun
  for a few years
• Neptune has 11 moons
• Like its sister gas planets, it has rings, but
  theyre dark and faint and currently we dont
  know what theyre made of
  
• The average cloud temperature on Neptune is cold!
  Averages range between -193 C to -153 C
  
• Neptunes revolution around the Sun takes 164.79
  Earth years
  
• Neptunes rotation on its axis takes only 16
  Earth hours 11 minutes

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Pluto

• Are you ready to make history? Pluto has never
  been visited by a spacecraft, so at 6 billion km
  from the Sun, well be the first to see this
  farthest (usually) planet up close.
• Pluto was discovered in 1930 and is in a class
  by itself. It doesnt fit with the rocky, inner
  planets or with its neighboring gas planets.
  Some scientists think Pluto and its moon, Charon,
  are escaped moons from Neptune, and it isnt a
  real planet at all.

Pluto, Hades in Greece, is the name of the Roman
god of the underworld. Because Pluto is so far
from the Sun, cold, and dark, naming it after the
Romans god of the dead makes sense!
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Pluto
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• As we learned at Neptune, Pluto is usually but
  not always the farthest planet from the Sun.
  It trades places with Neptune for a few years
  when its orbit crosses Neptunes orbit
• Its very cold on Pluto the average is -235 C
  to -210 C
  
• Pluto is so small, its smaller than many of
  other planets moons
  
• Pluto has one moon, Charon, thats only about
  half the size of Pluto. Because moons are
  usually a lot smaller than the planet they orbit,
  Pluto and Charon are sometimes called a double
  planet
• Pluto takes 248 Earth years to travel around the
  Sun
  
• Just like Venus, Pluto is in retrograde, meaning
  it spins counterclockwise, not clockwise like
  most planets
  
• Pluto spins once on its axis in 6.4 Earth days

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Going Home
Author

• We hope youve enjoyed your tour of the solar
  system! If youre thinking of taking another one
  of our tours to a single planet, you might want
  to get ready for your trip at one of these
  places
• Nine Planets
• NASAs Starchild
• Solarviews

The End
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Tour Guide

• Kelly Oldfield is a graduate student at
  Northeastern Illinois University, Spring 2003