1. Section 3-1 (Part 2)
Inner Planets

2. Objectives Define period of rotation Define period of revolution
Identify the characteristics of Mercury, Venus, Earth and Mars

3. Period of Rotation
The time it takes for a celestial body to spin or rotate once
Earth’s period of rotation is 24 hours or 1 day.

4. Period of Revolution
Time it takes for a celestial body to revolve around the Sun once
Earth’s period of revolution is days

5. Mercury

6. Mercury Closest planet to the Sun
3.2 light-minutes from the Sun
Doesn’t have an atmosphere like Earth does
Period of rotation = about 59 days
1 day on Mercury is equal to 59 days on Earth
Period of revolution = 88 days

7. Mercury
Gravity on Mercury is only 38% of the Earth’s gravity

8. Size of Mercury vs. Size of Earth

9. Venus

10. Venus: Earth’s Twin? Second-closest planet to the Sun
6 light-minutes from Sun
Has the hottest surface temperature of any planet.
Why doesn’t Mercury have the hottest surface?

11. Venus Venus has an atmosphere that is even thicker than Earth’s
Made up mostly of carbon dioxide
Atmosphere keeps the heat in (traps heat)

12. Venus Period of Rotation = 243 days BUT it spins in opposite direction
Earth spins Counterclockwise (Prograde rotation)
Venus spins clockwise (Retrograde rotation)

13. Venus
Gravity is 91% of Earth’s gravity

14. Size of Venus vs. Size of Earth

15. Earth
Why is Earth able to support life, but Venus and Mars are not?

16. Earth The Earth is at just the right distance from the Sun
Any closer and our oceans would boil away
Any further and oceans would be all ice
Water is the key to life

17. Earth 3rd planet from the Sun Period of rotation = 24 hours (1 day)
8.3 light-minutes from Sun
Period of rotation = 24 hours (1 day)
Period of revolution = days

18. Mars

19. Mars 4th planet from the Sun
12.7 light-minutes from Sun
Because of thin atmosphere and distance from Sun, Mars is very cold

20. Mars Period of rotation = about 25 hours
Very similar to Earth’s
Period of revolution = about 2 years
Gravity is 38% of Earth’s gravity

21. Mars
Mars is the most studied planet, other than Earth

22. Rover studying a rock on Mars

23. Water on Mars? Atmosphere is too thin Mars has ice, though.
Not enough pressure to keep water in liquid form
Any water would evaporate
Mars has ice, though.

24. Mountains on Mars
Olympus Mons: largest mountain/volcano in the entire Solar System

25. Mercury,Venus,Earth,Mars

26. What is common between Mercury, Venus, Earth and Mars?

27. Terrestrial Planets Similar to Earth Also called Inner Planets
Small, dense and made of rock
Also called Inner Planets
Include Mercury, Venus, Earth and Mars