Characteristics of the Solar System’s Rocky Planets

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 ), 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 ), Low Pressure, Clouds, Snow, Dust devils, Dust storms, Slight traces of Methane (CH )
  • 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!