The Solar System

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The Solar System

• 8th Grade Science

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The Solar System Evolves

• The solar system is the sun, the planets, and all
  the other objects that revolve around the sun.
• The nebular theory states that our solar system
  began as a huge cloud of dust and gas, which
  later condensed to form the sun and its nine
  planets.

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The Sun Forms First

• About 5 billion years ago, a star exploded in a
  huge supernova.
• The nebula that was home to the star begins to
  collapse and pull matter toward the center.
• At the center, a protosun forms.

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The Planets Form

• Gases and other matter surrounding the newly
  formed sun continue to spin around it.
• Gravity causes the matter to gather into small
  clumps, then into larger clumps called
  protoplanets.
• As the newly formed planets began to cool,
  smaller clumps of matter formed around them.
  Giving the planets their moons.

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Motions of the Planets

• In the second century B.C. Ptolemy proposed a
  theory that the Earth was at the center of the
  universe and that all objects moved in perfectly
  circular orbits.
• Nicolaus Copernicus then proposed a theory that
  the Earth and the other planets actually revolved
  around the sun.

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Motions of the Planets

• However, like Ptolemy, Copernicus also believed
  that the planets orbited in perfect circles.
• It was Johannes Kepler who realized after
  carefully studying the planets movements that the
  planets actually moved in oval orbits called
  ellipses.

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Revolutions and Rotations

• Kepler knew the planets orbited the sun, but how?
• Isaac Newton realized that a planets motion
  around the sun is a result of inertia and
  gravity.
• Inertia cause the planets to move in a straight
  line and gravity pulls them toward the sun.

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Revolutions and Rotations

• Another way to say a planet orbits the sun is to
  say it revolves around the sun.
• The time it takes a planet to make one revolution
  around the sun is called its period of
  revolution.
• Aside from revolving around the sun, planets also
  spin or rotate on their axis.
• The time it takes a planet to rotate on its axis
  is its period of rotation.

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A Trip Through the Solar System

• The planets of our solar system have a wide
  variety of surface and atmospheric features.
• Each planet has its own story to tell.

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Mercury

• Mercury is the closest planet to the sun and is
  its own crater-covered world.
• The craters on Mercury were created billions of
  years ago, but without weather, there has been no
  change.
• Mercury is one of the hottest and one of the
  coldest planets in the solar system.
• Mercury contains steep cliff and vast plains,
  most likely formed by volcanoes during the
  planets formation

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Venus-The Greenhouse in the Sky

• Venus has about the same diameter, mass, and
  density as Earth. For this reason it is called
  Earths twin.
• Astronomers were unsure about the surface of
  Venus because of its thick cloud cover. The lower
  level yellow clouds on Venus are made of sulfuric
  acid and carbon dioxide.
• The surface of Venus has an orange glow and is
  dotted with the remains of many volcanoes.

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Venus-The Greenhouse in the Sky

• The temperatures on Venus can climb to 480C,
  which is hotter than the surface of Mercury.
• The heat from the sun caused the water on Venus
  to evaporate into the atmosphere causing a
  tremendous greenhouse effect. This eventually
  caused the oceans to evaporate completely.
• Venus also has a retrograde rotation, which means
  it rotates from east to west.

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Mars-The Rusty Planet

• As you approach Mars, the first thing you would
  notice is the reddish color. This is because
  Martian soil is covered in rust!
• The surface of Mars is rocky and covered in
  craters.
• Mars gives evidence to a very active past. It is
  also home to the largest know volcano in the
  solar system
• Today there is no liquid water on Mars, but
  frozen water can be found on Mars polar ice caps.

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The Asteroid Belt

• On your way from Mars to Jupiter you will enter
  the asteroid belt.
• The asteroid belt contains hundreds of thousands
  rocks and flying mountains.
• Asteroids are made of rocks, metals, or a
  combination of the two.
• Most asteroids are small and irregularly shaped.
• The asteroid belt formed from pieces of matter
  that failed to join during the solar systems
  formation.
• Scientists suspect that Jupiters gravitational
  pull kept the asteroids from coming together

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Jupiter

• Jupiter is the largest planet in our solar
  system.
• Jupiter is made of primarily hydrogen and helium
  gases.
• Scientists believe that if Jupiter had grown
  larger during its formation, gravity might have
  caused nuclear fusion to occur and a star to
  form.
• One of Jupiters most well know feature is the
  Great Red Spot, which is a huge hurricane type
  storm that is three times the size of Earth and
  has lasted for more than 100 years.
• Due to the pressure near the center of the
  planet, the dense clouds become an ocean of
  liquid hydrogen.

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Jupiter

• This liquid metallic layer of Jupiter is the
  cause of its gigantic magnetic field called the
  magnetosphere.
• Jupiter is also strange in the fact that it gives
  off more heat than it receives from the sun.
• It also has a total of 16 moons that circle it,
  but there are 4 very large moons discovered by
  Galileo.
• IO is the closest of Jupiters moons and is very
  young and active.
• EUROPA is ice covered and extremely smooth due to
  its volcano that spews water and ammonia ice.
• GANYMEDE is Jupiters largest moon and is the
  largest in the solar system. It is about 1/2 rock
  and 1/2 water and is the only other object in the
  solar system known to have earthquakes.
• CALLISTO is the most heavily cratered object in
  the solar system and is a very quiet moon.

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Saturn-A World of Many Rings

• Saturn is surrounded by seven major rings made up
  of icy particles.
• Saturn is made mainly of hydrogen and helium
  gases and spins very fast on its axis, which
  causes its poles to flatten.
• Saturn, like Jupiter, also has violent storms.
• Saturns clouds also form the colored bands we
  see.
• Saturn also has a very small density and would
  actually float in water.
• Saturn has 21 known moons with the largest being
  Titan.

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Uranus-A Planet on Its Side

• Uranus is the seventh planet in our solar system
  and is almost twice as far from the sun as
  Saturn.
• Uranus is also a gas planet made of mostly
  hydrogen, helium, and methane.
• Strong evidence was found that Uranus is covered
  by an ocean of superheated water than may have
  formed from melted comets.
• The axis on which Uranus rotates is one the most
  unusual features. The axis is tilted at an angle
  of about 90. This makes it look like it is
  tipped completely on its side.

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Neptune

• Upon examining the orbit of Uranus, astronomers
  noticed that there must be an object beyond
  Uranus.
• Neptune is a giant bluish world.
• Neptune is often called a twin to Uranus because
  they are about the same size, mass, and
  temperature.
• Neptunes surface is probably and ocean of water
  and liquid methane, covering a rocky core.
• Data was also found to indicate that Neptune has
  five rings made of dust particles.
• Neptune also has at least 8 moons the biggest and
  most well known being Triton.

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Pluto-A Double Planet

• Pluto is little more than a moon-sized object
  than may be an escaped moon of Neptune.
• Pluto is made of icy gases such as methane.
• Pluto is the only planet with an atmosphere on
  its sunny side and none on its dark side.
• Pluto also has a moon that is so close in size
  that it may be double planet.

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Planet X-The Tenth Planet?

• After discovering Pluto, scientists realized that
  it was too small to be pulling on Uranus and
  Neptune.
• This causes scientists to believe there is
  another planet as far as 80 billion kilometers
  from the sun pulling on the planets causing their
  strange orbits.
• Other scientists feel that they are being pulled
  on by a Brown Dwarf or possibly a black hole.

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Comets

• Most comets come from the Oort cloud, which is a
  vast collection of ice, gas, and dust.
• The pull of gravity from a local star pulls parts
  of this cloud out into space.
• Comets are made up of this ice, gas, and dust,
  which form a cloud around the core as it heats
  up.

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Meteoroids, Meteors, and Meteorites

• Meteoroids are chunks of metal or stone that
  orbit the sun.
• When the meteoroid enters the atmosphere,
  friction causes it to burn. The streak of light
  in the sky is called a meteor.
• Most meteors burn up in the atmosphere, but a few
  strike the Earths surface and are called
  meteorites.

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Exploring the Solar System

• Rocketry
• Rocketry is based on Newtons third law of
  motion.
• In a reaction engine, such as a rocket, the
  rearward blast of exploding gases causes the
  rocket to shoot forward.
• However, rockets must be able to escape Earths
  gravitational pull.

• Escape Velocity
• In order for a rocket to escape Earths pull, the
  rocket must achieve the proper velocity.
• The escape velocity of a planet is determined by
  the mass of the planet and the distance of the
  rocket from the planets center.
• Rockets also need a fuel source that will
  continue to burn.

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Live Long and Prosper!!!