PLANET NOTES
MERCURY a terrestrial (rocky) planet
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Closest planet to the Sun (so shortest revolution period)
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Revolves around the Sun the fastest. 1 rev= 88 Earth days
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1 rotation= 59 Earth days
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Smallest planet in our solar system
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Surface is covered with craters, one called the Caloris Basin is the size of Texas
(largest in the SS)
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No moons
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Weak atmosphere
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Temp ranges from 800 degrees F to –300 degrees F (largest temp swing in SS)
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Ice found deep in craters of the N and S poles
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Core is mainly iron
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Size is a little more than 1/3 the size of Earth; 1 ½ times the size of Earth’s Moon
VENUS a terrestrial (rocky) planet
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1 rev= 225 Earth days and 1 rotation= 243 days: day is longer than year
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Rotates in retrograde motion (clockwise), opposite of most planets
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2nd brightest in our night sky, after the Moon
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About the same size as Earth (nicknamed Earth’s Sister Planet or Earth’s twin)
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Atmosphere of carbon dioxide and sulfuric acid
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Heat is trapped by clouds- greenhouse effect out of control (900 degrees F) –
hottest planet
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Surface is covered in rocks and volcanoes (estimated 100,000)
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Called the morning and evening star
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No moons
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Winds are about 240 mph and air pressure is 90x that of Earth’s
EARTH a terrestrial (rocky) planet
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93 million miles from the Sun, 1 AU
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1 moon that is large compared to the size of Earth (named Moon) – it is ¼ the size
of Earth
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Water exists in three forms: solid, liquid, and gas
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Atmosphere= Nitrogen, and Oxygen, with traces of Carbon Dioxide and Argon
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1 revolution= 365.25 days
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1 rotation= 24 hours
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Only place known that is capable of supporting life
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Largest of the terrestrial planets
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Core is made of iron
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Tilt of the Earth on its axis causes the seasons
MARS a terrestrial (rocky) planet
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1 rev= 687 days (2 Earth years)
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1 rotation= 24 1/2 hours
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Two polar ice caps
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Has giant dust storms (dust devils)
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“The Red Planet” due to the iron that has rusted, coloring the soil red
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2 tiny moons: Phobos and Deimos (thought to be asteroids caught in gravity)
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Average temperature= 60 degrees F to –10 degrees F
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Surface is rocky and dusty
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Core= iron, nickel, and sulfur
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No tectonic plates
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Atmosphere= carbon dioxide, very thin, has weather
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Has the highest mountain in the Solar System: Olympus Mons (16.7 miles
high—3x Everest)
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Has the largest canyon in the Solar System: Valles Marinaris
JUPITER gas planet
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First of the gas planets, with no solid surface (outer planets)
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1 rev= 12 Earth years
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1 rotation= 10 hours (fastest among planets in SS)
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3rd brightest object in our night sky (after the Moon and Venus)
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63 moons: largest 4 are Callisto, Europa (which has water), Io, and Ganymede
(largest moon in the Solar System)
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Atmosphere= 90% H and 10% He (not big enough or hot enough to be a star)
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Colored bands are the different layers of gases
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Largest planet in the SS
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“The Great Red Spot”- 300 year storm with winds about 225 mph
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Gravity deflects asteroids from hitting Earth
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Gives off more energy than it receives from the Sun
SATURN gas planet
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1 rev= 29.5 Earth years
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1 rotation= 10.5 hours
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Rings- miles wide and a mile thick, made of ice, rock, and dust
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60 moons- Titan (the largest of Saturn’s moons, and the 2nd largest moon in the
Solar System) has liquid ethane and may have an atmosphere like a young Earth
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Atmosphere= H, He, and traces of methane-very cold, while the core intensely hot
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Gas from the atmosphere is compressed into a liquid state
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“The Dragon Storm”- winds up to 1,100 mph
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Appears as a faint yellow object
URANUS gas planet
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“Quirky” planet- tipped on it’s side more than 90 degrees
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Equator runs from North to South
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Rotates clockwise, like Venus
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Has rings that are hard to see because they’re made of dark rocks
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27 moons
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Average –350 degrees F year round
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Appears blue-green because the methane absorbs the red light
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Atmosphere= H, He, and methane
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Ocean of ammonia underneath the atmosphere
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Theory that there are millions of diamonds in the core
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1 rev= 84 Earth years and 1 rotation= 18 hours
NEPTUNE
gas planet
 1 revolution= 165 Earth years
 1 rotation= 16 hours
 Gas giant
 Slightly smaller than Uranus
 Has rings made of dark rocks
 Highest winds in the solar system were discovered here (over 1,200 mph)
 Atmosphere= methane, gives its blue color
 12 moons
 Weather= storms- look like dark blue spots (one was called The Great Dark Spot
but disappeared in 1994; another storm in opposite hemisphere developed in
1995)
PLUTO AND DWARF PLANETS
 5 known dwarf planets: Pluto, Ceres, Eris,
MakeMake, and Haumea
 Known dwarf planets- located in the Asteroid Belt and Kuiper Belt
 No spacecraft has visited Pluto yet
 Pluto is about 1/5 the size of Earth
 Pluto’s temperature is about –400 degrees F
 Pluto- discovered in 1930, demoted in 2006
 Pluto crosses Neptune's orbit
 Pluto has 3 moons: Charon (1/2 size of Pluto)
Nix and Hydra
 dwarf planet:
1. orbits the Sun
2. enough gravity to be a sphere shape
3. not a satellite
4. has not cleared its neighborhood