Difference Between Inner And Outer Planets (With Examples)

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Inner Planets/Terrestrial Planets

The inner planets also referred to as terrestrial planets are the four planets closest to the Sun. they include: Mercury, Venus, Earth and Mars. These planets are smaller and denser than their counterparts (outer planets) and have few to no moons or rings circling them. Mercury and Venus do not have moons, Earth has one and Mars has two. All terrestrial plants have rocky surfaces that feature mountains, plains, valleys and other formations such as impact craters and tectonic features as well, such as rift valleys and volcanoes.

These planets are also composed largely of refractory minerals such as the silicates, which form their crusts and mantles and metals such as iron and nickel which form their cores. Three of the four inner planets (Venus, Earth and Mars) have atmospheres substantial enough to generate weather. The inner planets also have shorter orbits around the Sun and they all spin more slowly.

What You Need To Know About Inner Planets

  • They are closer to the Sun.
  • Inner planets are mostly composed of rocky surfaces.  
  • They are commonly referred to as ‘’terrestrial planets’’ because they have solid, rocky surface which is quite similar to the desert and mountainous areas on the Earth.   
  • They have either no moons or few moons. Mercury and Venus have no moons, Earth has one moon and Mars has two tiny moons.
  • They have no planetary ring.
  • They take a short time to complete one revolution.  
  • Inner planets lie inside the asteroid belt.
  • Inner planets spin slowly.
  • Inner planets take lesser time to complete an orbit around the Sun.
  • They are characterized by thin atmospheres and high temperatures.
  • Most of the inner planets are smaller than the outer planets. Earth is the largest inner planet while mercury is the smallest.
  • The inner planets are Mercury, Venus, Earth, and Mars.

Outer Planets/Gas Giants

The outer planets are the four planets that are farther from the Sun as well as farther from Earth. They include: Jupiter, Saturn, Uranus and Neptune. The outer planets are also referred to as Gas giants or Jovian planets. These planets are made primarily of gases (hydrogen and helium) and liquids. They have thick gaseous outer layers and liquid interiors.

The outer planets are much larger than the inner planets. They make up approximately 95% of the mass of the celestial bodies that orbit the Sun. Jupiter and Saturn are substantially larger than Uranus and Neptune, and each pair of planets has a somewhat different composition. The inner and outer planets are separated by asteroid belt.

All of these planets have numerous moons. They all also have planetary rings, composed of dust and other small particles that encircle the planet in a thin plane. For example Jupiter has more than 60 moons including the four largest, the Galilean Moons.

The outer planets spins fast on their axis and takes a long time to go around the Sun. For example one Jupiter year is as long as 12 Earth years.

What You Need To Know About Outer Planets

  • They are further away from the Sun.
  • Outer planets are generally made up of Gases primarily hydrogen and helium.
  • They are also referred to as Giant planets and are composed of low-boiling-point materials (gases or ices), rather than rock or other solid matter. 
  • They have dozens of moons.
  • They have planetary rings. Saturn has seven rings, Neptune has six rings and Uranus and Jupiter have faint rings systems.
  • They take a long time to complete one revolution.
  • Outer planets lie beyond the asteroid belt.
  • Outer planets spin faster than inner planets.
  • Outer planets take a longer time to orbit around the sun due to their greater distance from the Sun.
  • Characterized by thick atmospheres and cold temperatures.
  • Most of the outer planets are very large. Jupiter is the largest while Neptune is the smallest.
  • Outer planets are Jupiter, Saturn, Uranus and Neptune. 

Also Read: Difference Between Solar And Lunar Eclipse

Difference Between Inner And Outer Planets In Tabular Form

BASIS OF COMPARISON INNER PLANET OUTER PLANET
Position They are closer to the Sun.   They are further away from the Sun.  
Composition Inner planets are mostly composed of rocky surfaces.    Outer planets are generally made up of Gases primarily hydrogen and helium.  
Alternative Name They are commonly referred to as terrestrial planets. They are also referred to as Giant planets or Jovian Plants.
Moon They have either no moons or few moons. They have dozens of moons.  
Planetary Rings They have no planetary ring.   They have planetary rings.
Revolution They take a short time to complete one revolution.    They take a long time to complete one revolution.  
Position Around Asteroid belt Inner planets lie inside the asteroid belt.   Outer planets lie beyond the asteroid belt.  
Spinning Inner planets spin slowly.   Outer planets spin faster than inner planets.  
Orbiting Around The Sun Inner planets take lesser time to complete an orbit around the Sun.   Outer planets take a longer time to orbit around the sun due to their greater distance from the Sun.  
Atmosphere & Temperature They are characterized by thin atmospheres and high temperatures.   Characterized by thick atmospheres and cold temperatures.  
Size Most of the inner planets are smaller than the outer planets. Earth is the largest inner planet while mercury is the smallest.   Most of the outer planets are very large. Jupiter is the largest while Neptune is the smallest.  
Examples The inner planets are Mercury, Venus, Earth, and Mars.   Outer planets are Jupiter, Saturn, Uranus and Neptune.   

Also Read: Difference Between Equinox And Solstice