Activities

1. List the planets in order starting with the closest to the Sun.
   
   
2. Which planets have a known solid surface?

3. How does the size of the inner planets compare to the size of the outer planets?
   
   
4. How does the composition of the inner planets compare to the composition of the outer planets?
   
   
5. How is average temperature related to distance from the Sun? Are there any exceptions to this pattern? If yes, why?
   
   
6. What characteristics allow life to exist on Earth?

7. Why do the outer planets have rings, and the inner planets do not?

Answer Key/Rubric

1. The planets nearest to farthest are: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune.
   
   
2. Mercury, Venus, Earth, and Mars have a known solid surface.
   
   
3. The inner planets are the four smallest planets (Mercury, Venus, Earth, and Mars) and the outer planets are the four largest planets (Jupiter, Saturn, Uranus, and Neptune).
   
   
4. Sample response: The inner planets have a solid surface and are known as the terrestrial planets. The outer planets are known as the “gas giants” because they do not have a solid surface and are composed of gas.  Uranus and Neptune also have ices in their atmosphere.
   
   
5. Sample response: Generally, as the distance from the Sun increases, the average temperature decreases. However, Venus’ average temperature is higher than Mercury’s average temperature, although Mercury is closer to the Sun. This is because Venus’ atmosphere is largely composed of carbon dioxide which keeps heat trapped in (like the Greenhouse Effect on Earth).
   
   
6. Sample response: Life exists on Earth because its atmosphere provides necessary gases to sustain life and consists of liquid water. Its atmosphere also allows temperatures to stay even and reasonable. In addition, it keeps water in its appropriate form without freezing entirely, or evaporating entirely.  The distance from the Sun provides an appropriate temperature for life to exist.

7. Acceptable responses may include but are not limited to (based on different theories):

• When our solar system formed from a cloud of gas and particles, some of the dust from the explosion became terrestrial planets, or moons, while others lingered and eventually was captured by the gravitational pull of the outer planets.
• Since some of the rings are composed of icy particles, the inner planets would be too warm for them to exist.
• Since the outer planets are bigger, they have a stronger gravitational pull, and are able to keep more objects in its orbit.