Planets of the Solar System

The Habitable Zone

The Habitable Zone

Orbital Periods Sidereal Period: A 360° revolution of one celestial body around another as that the object returns to the same position relative to the fixed stars projected in the sky. Synodic Period: The elapsed time for the repeated cycles for celestial bodies as observed from the Earth's surface; where planets return to the same position in Earth’s sky. Orbital periods are typically measured in Earth days or Earth years.

Mercury Closest planet to the Sun Known since ancient times Sidereal Period: 87.89 days Sidereal Day: 58.65 days Surface Temperature: 100 – 700 K (-280 – 800 F)

Mercury 0.38 x the radius of Earth 0.98 x the density of Earth Very large iron core The detected magnetic field indicates the core may be liquid ~60% of Mercury’s mass is contained in its core Thick solid crust Lack of volcanism and tectonic motion

Venus Second planet from the Sun Known since ancient times Often Called Earth’s Sister Planet Known since ancient times Sidereal Period: 244.7 days Sidereal Day: 583.9 days Average Surface Temperature: 730 K (854 F)

Venus 0.95 x the radius of Earth 0.95 x the density of Earth Thinner crust Volcanically Active Atmosphere 90 x more mass than Earth’s Extreme greenhouse effect

Phases of Planets Mercury Difficult to see the full phase

Phases of Planets Venus

Earth Third planet from the Sun Sidereal Period: 365. days Sidereal Day: 1 days Average Surface Temperature: 290 K (62 F) 1 Moon

Earth Solid Inner Core Liquid Outer Core Liquid Mantle Solid, Rocky Crust

Mars Fourth planet from the Sun Known since ancient times Sidereal Period: 686.9 days Sidereal Day: 1.026 days Average Surface Temperature: 210 K (-82 F) 2 Moons

Mars 0.53 x the radius of Earth 0.71 x the density of Earth

Comparing the Inner Planets

Asteroid Belt