Skip to main content
Geosciences LibreTexts

1.25: Planets and Planetary Systems of the Solar System

  • Page ID
    9734
    • Contributed by Miracosta Oceanography 101
    • Sourced from Miracosta)

    A planet is a large spherical celestial body moving in an elliptical orbit around a star. A planetary system is a set of gravitationally bound celestial objects in orbit around a star or star system. Planets with orbiting moons are planetary systems. The Solar System consists of four inner rocky planets, four outer gas planets, and orbiting belts of asteroids, comets, planetesimals, and other objects under the gravitation influence of the Sun.

    The 4 Inner Rocky Planets

    Mercury

    Venus

    Earth

    Mars

    Figure 1.65. Mercury Figure 1.66. Venus Figure 1.67. Earth Figure 1.68. Mars
    • a rocky planet
    • no atmosphere
    • no moons
    • planet radius: 1,516 miles (2440 km)
    • average distance from sun: 36 million miles (58 million km)
    • orbital period: 88 days
    • gravity: 3.7 m/sec2
    • a rocky planet
    • hot atmosphere, mostly CO2 (with a sulfur-rich cloud cover)
    • no moons
    • planet radius: 3,760 miles (6050 km)
    • average distance from sun: 67.24 million miles (108 million km)
    • rotation (day): -243 day (it rotates backwards!)
    • orbital period: 224.7 days
    • gravity: 8.87 m/sec2
    • a rocky planet with oceans, ice cap, and atmosphere
    • supports life!
    • one moon (the Moon!)
    • planet radius: 3,959 miles (6370 km)
    • average distance from sun: 92.96 million miles (150 million km)
    • rotation (day): 24 hours
    • orbital period: 365.24 days
    • gravity: 9.8 m/sec2
    • a rocky planet
    • has ice caps at poles
    • thin atmosphere, mostly CO2
    • 2 small moons: (Phobos and Deimos)
    • planet radius: 2,106 miles (3390 km)
    • average distance from sun: 141.6 million miles (228 million km)
    • rotation (day) 24.67 hours
    • orbital period: 687 days
    • gravity:

    The 4 Outer Gas Planets (or Planetary Systems)

    Jupiter Saturn Uranus Neptune

    Figure 1.69. Jupiter

    Figure 1.70. Saturn Figure 1.71. Uranus Figure 1.72. Neptune
    • largest of the gas planets
    • mostly hydrogen and helium
    • has 67 moons, of which 4 are much larger than other moons.
    • very active storms are visible in its atmosphere.
    • planet radius: 43,441 mile 70,000 km)
      *average distance from sun:
      483.8 million miles (779 million km)
    • orbital period: 12 years
    • rotation (day): 9 hr, 56 min
    • a gas planet famous for its visible rings (mostly dust, ice, and rock fragments).
    • Currently has 62 moons, including Titan, the largest in the Solar System.
    • planet radius: 36,184 miles (36,200 km)
    • average distance from sun:
      888.2 million miles (1.42 billion km)
    • orbital period: 29 years
    • rotation (day): 10 hr, 42 min
    • a gas planet
    • has 5 medium-sized moons (many smaller ones too)
    • planet radius:15,759 miles (25,400 km)
    • average distance from sun:
      1.784 billion miles (2.87 billion km)
    • orbital period: 84 years
    • rotation (day): 17 hr, 14 min
    • the outermost gas planet
    • has 13 known moons
    • planet radius: 15,299 miles (24,620 km)
    • average distance from sun:
      2.795 billion miles (4.5 billion km)
    • orbital period: 165 years
    • rotation (day): 16 hr, 6 min
    • Was this article helpful?