The four Inner Planets are closely spaced and are known as the Terrestrial Planets because
they are
1) small,
2) dense.
3) and rocky.
Inner Planets
Planet
In our solar system, a planet is a celestial body that
1) must be in orbit around the sun,
2) has sufficient mass to be round in shape,
3) and has "cleared the neighborhood" around its orbit of other objects.
(definition by IAU in 2006)
Mercury
Distance from Sun: 58 million km
Orbital Speed: 47.8 km/s
Period of rotation (length of day): 59 days
Period of revolution (length of year): 88 days
Type of Rotation: Prograde
Approximate diameter: 4,878 km
Surface gravity: 38%
Number of moons: 0
Interesting Facts: no atmosphere. 1 year =1.5 days
Venus
Distance from Sun: 108 million km
Orbital Speed: 35 km/s
Period of rotation (length of day): 243 days
Period of revolution (length of year): 225 days
Type of Rotation: Retrograde
Approximate diameter: 12,104 km
Surface gravity: 91%
Number of moons: 0
Interesting Facts: most dense atmosphere. Hottest planet because of greenhouse effect
Earth
Distance from Sun: 150 million km
Orbital Speed: 29.8 km/s
Period of rotation (length of day): 24 hours
Period of revolution (length of year): 365 days
Type of Rotation: Prograde
Approximate diameter: 12,756 km
Surface gravity: 100%
Number of moons: 1
Interesting Facts: Liquid water, tectonic forces, supports life
Mars
Distance from Sun: 228 million km
Orbital Speed: 24.2 km/s
Period of rotation (length of day): 25 hours
Period of revolution (length of year): 687 days
Type of Rotation: Prograde
Approximate diameter: 6,794 km
Surface gravity: 38 %
Number of moons: 2
Interesting Facts: largest mountain-Olympus/Mons. Has a thin CO2 atmosphere
Outer Planets
Outer Planets are spaced further apart and known as Gas Giants for their
1) Large size
2) and Composition (Gas).
Jupiter
Distance from Sun: 778 million km
Orbital Speed: 9.7 km/s
Period of rotation (length of day): 10 hours
Period of revolution (length of year): 12 years
Type of Rotation: Prograde
Approximate diameter: 142,984 km
Surface gravity: 236%
Number of moons: 63
Interesting Facts: Largest Planet. Great Red Spot is a large storm
Uranus
Distance from Sun: 2,827million km
Orbital Speed: 6.8 km/s
Period of rotation (length of day): 17 hours
Period of revolution (length of year): 84 years
Type of Rotation: Retrograde
Approximate diameter: 51,118 km
Surface gravity: 89%
Number of moons: 21
Interesting Facts: Spins on its side. Blue green color
Saturn
Distance from Sun: 1424 million km
Orbital Speed: 9.7km/s
Period of rotation (length of day): 12 hours
Period of revolution (length of year): 30 years
Type of Rotation: Prograde
Approximate diameter: 120,536 km
Surface gravity: 92%
Number of moons: 33
Interesting Facts: Rings visible from Earth
Neptune
Distance from Sun: 4486 million km
Orbital Speed: 5.4 km/s
Period of rotation (length of day): 16 hours
Period of revolution (length of year): 165 years
Type of Rotation: Prograde
Approximate diameter: 49,528 km
Surface gravity: 112%
Number of moons: 13
Interesting Facts: Methane Atmosphere, Great Dark Spot. Incomplete Rings