1. Planets of the Solar System

2. The Habitable Zone

3. The Habitable Zone

4. 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.

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

6. 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

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

8. 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

9. Phases of Planets
Mercury
Difficult to see the full phase

10. Phases of Planets
Venus

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

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

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

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

15. Comparing the Inner Planets

16. Asteroid Belt