Transcript The Inner Planets Notes How Many Planets?

The Inner Planets Notes
How Many Planets?
• How many planets are there in our Solar
System? 9? 8?
• 13 Planets!!!
– 4 terrestrial planets
– 4 gas planets
– 5 dwarf planets
Planet Types
• Terrestrial Planets
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“rocky planets”
Mercury, Venus, Earth, Mars
Orbit the Sun
Clear their own orbits of other objects
• Dwarf Planets
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Made of rock and ice
Ceres, Pluto, Haumea, Makemake, Eris
Orbit the Sun
Too small to fully clear orbits, often found in Asteroid
Belt or Kuiper Belt
Order of the Solar System
• Sun
• Inner Planets
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Mercury
Venus
Earth
Mars
• Asteroid Belt
– Asteroids
– Ceres
• Outer Planets
• Kuiper Belt
• Oort Cloud
1st Rock - Mercury
• Dead planet,
shrinking
• Extreme
temperatures
• Thin
atmosphere
• Fast orbit, slow
rotation, year
shorter than day!
• No moons
• Smallest planet
2nd Rock - Venus
• Bright in night sky
• Earth’s “evil twin”,
same size, same
materials
• Thick, deadly
atmosphere,
massive lightning
• Heavily volcanic
• Hottest planet,
runaway
greenhouse effect
• No moons
3rd Rock - Earth
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One moon
Only planet with life
Ocean’s cover 75% of surface
Study of Earth: Geology (3rd & 4th Quarter)
4th Rock - Mars
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The Red Planet
Half the size of Earth
Thin CO2 atmosphere
Used to have thicker
atmosphere, liquid
water on surface,
maybe life
• Most studied and
visited planet
• 2 moons, Phobos &
Deimos
5th Rock - Ceres
• Dwarf planet
• Largest object in
Asteroid Belt
• 1st a planet,
then asteroid,
now dwarf
Asteroid Belt
• Asteroid Belt between Mars & Jupiter
• Asteroids: small, rocky objects, most under 1 km in
diameter
• Over 100,000 asteroids in the belt
• “leftover” pieces from solar system creation
• Some have large elliptical orbits that bring them closer to
the Sun than the Earth, and could smash into Earth!!!