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8.5: Characteristics of the Solar System’s Rocky Planets

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    64130
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    Comparison of the Rocky Planets

    Mercury

    Characteristic — Current State

    • Impact Craters — Yes
    • Tectonic Craters — Yes; not active
    • Volcanoes — Yes; not active
    • Atmosphere — No real atmosphere
    • Water — Yes; water and ice in craters at the poles
    • Erosion — No
    • Dunes — No
    • Polar Caps — No
    • Satellites — No
    • Life — Unknown

    The Bottom Line…

    • Looks like the Moon; heavily cratered
    • No real atmosphere
    • No seasons
    Image of Mercury.
    Public Domain | Image courtesy of NASA / JPL-CALECH.

    Venus

    Characteristic — Current State

    • Impact Craters — Yes
    • Tectonic Craters — Yes
    • Volcanoes — Yes; over 1,600 volcanoes – most on one body in the Solar System
    • Atmosphere — Carbon Dioxide (CO2), Sulfuric Acid (H2SO4), High Pressure, Clouds, Odd Polar Vortex
    • Water — No
    • Erosion — Yes
    • Dunes — Yes
    • Polar Caps — No
    • Satellites — No
    • Life — Unknown

    The Bottom Line…

    • Called Earth’s twin
    • Extreme Greenhouse effect
    • Rains sulfuric acid
    • Polar Vortex
    Image of Venus.
    Public Domain | Image courtesy of NASA / JPL-CALECH.

    Earth

    Characteristic — Current State

    • Impact Craters — Yes
    • Tectonic Craters — Yes
    • Volcanoes — Yes
    • Atmosphere — Nitrogen (N), Oxygen (O 2 ), Clouds, Rain, Snow
    • Water — Vapor, Liquid, and Ice → Primarily a water planet
    • Erosion — Yes
    • Dunes — Yes
    • Polar Caps — Yes
    • Satellites — One, Moon
    • Life — Yes

    The Bottom Line…

    • Water Planet
    • Big moon – double planet
    • Life everywhere
    Image of Earth.
    Public Domain | Image courtesy of NASA / ESA.

    Moon

    Characteristic — Current state

    • Craters
    • Evidence of past volcanic, tectonic activity
    • No atmosphere
    • Water ice found in a lunar south pole crater
    • Probably formed from a collision with Earth
    • Looks like Mercury…
    Image of the Moon.
    CC BY-SA 3.0 | Image courtesy of Wikimedia Author: Gregory H. Revera.

    Mars

    Characteristic — Current State

    • Impact Craters — Yes; a very large impact crater Borealis Basin (largest known in the Solar System), 6,600 miles across
    • Tectonic Craters — Yes, still active?
    • Volcanoes — Yes, not active; One of the largest volcanoes in the Solar System; Olympus Mons
    • Atmosphere — Carbon Dioxide (CO 2 ), Low Pressure, Clouds, Snow, Dust devils, Dust storms, Slight traces of Methane (CH 4 )
    • Water — Both liquid & water ice
      • Subsurface liquid water aquifers?
      • 2% water in soil
    • Erosion — Yes
    • Dunes — Yes
    • Polar Caps — Yes
    • Satellites — Two; Deimos and Phobos
    • Life — Unknown; we are actively searching for life

    The Bottom Line…

    • Is liquid water still flowing?
    • Very light compared to Venus and Earth (less dense)
    • Life?
    Image of Mars.
    Public Domain | Image courtesy of NASA / JPL-CALECH.

    Deimos and Phobos

    Characteristic — Current state

    • Craters
    • No Atmosphere
    • Very small
    • Captured asteroids or result of collisions with Mars
    Image of Deimos and Phobos from Mars.
    Public Domain | Images courtesy of NASA/JPL-Caltech/University of Arizona.

    Consider this…

    How did elementary school kids used to remember the order of the planets from the Sun? A simple mnemonic: My Very Educated Mother Just Served Us Nine Pizzas! (Mercury Venus Earth Mars Jupiter Saturn Uranus Neptune Pluto) But with the demotion of Pluto as a full planet, the pizzas went away, so now it is My Very Educated Mother Just Served Us Nachos!

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