Our Solar System

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Our Solar System
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Planets

• An object that orbits one or more stars and is
  not a star itself
• Spherical
• Does not share its orbit with another object
• Inner planets (Terrestrial planets) are Mercury,
  Venus, Earth, and Mars)?
• Outer planets (Gas planets) are Jupiter, Saturn,
  Uranus and Neptune.

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ORDER OF THE PLANETS
Mercury
My
Venus
Very
Earth
Educated
Mars
Mother
Jupiter
Just

Saturn
Served
Uranus
Us

Nuts
Neptune
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Planetary Motion

• Venus and Mercury stay near the Sun and can only
  be seen in the early morning or early evening.
• Mars, Jupiter and Saturn move westward along with
  the fixed stars due to Earths rotation.
• Retrograde motion happens when Earth catches up
  with and passes an outer planet in its orbit. It
  appears that the planet makes a looping motion in
  the sky.

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Distances Between Planets

• Planets lie so far apart that using kilometers to
  measure it, is not meaningful.
• Astronomers use astronomical unit (AU), which is
  equal to the distance between Earth and the Sun
  (150million km)?
• The average distance between the Sun and an
  object that is orbiting it is called the orbital
  radius.

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Mercury

• Craters, rocky
• Small (only a bit larger than our moon)?
• No atmosphere so large temperature differences
  between day and night
• No moons

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Venus

• Size and composition similar to Earth
• Shrouded in thick clouds
• Constantly rains sulfuric acid (acid rain)?
• Atmosphere contains CO2 and nitrogen.
• Some areas that are flat, volcanoes, cracks
  called rifts.
• Hot because the atmosphere traps the heat.
• No moons

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Earth

• Only planet that has life (so far)?
• Lots of water
• Atmosphere nitrogen, oxygen and water vapor
  mainly.
• Surface is constantly changing.
• 1 moon

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Mars

• Red because the iron in the rock
• Volcano 3 times larger than Mt Everest
• Very deep canyon (8km deep)?
• Strong winds
• 2 polar ice caps
• Thin atmosphere made mainly of CO2
• 2 moons

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Jupiter

• Largest
• Great Red Spot a storm of hydrogen and helium
  clouds.
• Shortest days of all planets (10hours)?
• Rings made of ice particles that are very thin.
• 61 moons

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Saturn

• Elaborate system of rings made of ice particles
• Rings are 250 000km wide
• Composed of mainly hydrogen and helium
• 60 moons

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Uranus

• Ring system made of ice and dust
• Methane gas in its atmosphere (blue-green
  colour)?
• Atmosphere also has hydrogen and helium
• Unusual rotation - flipped on its side
• 27 moons

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Neptune

• Atmosphere is similar to Uranus.
• Very thin ring system made of ice particles.
• 13 moons

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Trans-Neptunian Objects

• Objects that circle the Sun beyond the orbit of
  Neptune
• Found in the Kuiper Belt
• Astronomers think that it is made of fragments
  left over from the formation of the solar system.
• Pluto is found in the Kuiper Belt and is known as
  a dwarf planet.

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Oort Cloud

• At the farthest reaches of the Suns
  gravitational influence is a spherical cloud of
  icy fragments of debris called Oort.

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Comets

• Most start in the Kuiper Belt and the Oort cloud.
• Sometimes the comet gets too close to Jupiter.
• Jupiters gravitational force will either capture
  the comet or nudge it closer to the Sun
• When it gets close to the Sun, the radiation from
  the Sun releases the gases and particles in the
  comet.
• The wind from the Sun make the tail of the comet.

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Asteroids

• Small, non-spherical objects that are thought to
  be debris left over from the formation of the
  solar system.
• Most are in the asteroid belt found between Mars
  and Jupiter

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Meteoroids vs Meteors vs Meteorites

• Meteoroids Pieces of rock moving through space.
• Meteors a meteoroid that hits Earths atmosphere
  and burns up due to atmospheric friction.
• Meteorites a meteoroid that is large enough to
  pass through Earths atmosphere and reach the
  ground without being totally burned up.

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The Impact of Impacts

• An asteroid about the size of a mountain struck
  Earth 65 million years ago.
• There were huge changes on Earth because of it.
• Extinctions dinosaurs
• Impact craters (Nunavut and Arizona)?
• Probably created huge winds and falling rock.