Year 7 Science · Unit 4 · Lesson 16
Apply Worksheet
Learning Goals
Inner or outer?
For each planet, write whether it is an inner planet or an outer planet, then write one word describing what it is mostly made of (rock, or gas and ice).
| Planet | Inner or outer? | Mostly made of |
|---|---|---|
| Earth | ||
| Saturn | ||
| Mercury | ||
| Neptune |
Real-world context
Mercury is the closest planet to the Sun, so you might expect it to be the hottest. Yet Venus, which is further from the Sun, is actually the hottest planet of all. The reason is that Venus is wrapped in a very thick atmosphere full of carbon dioxide. This thick blanket of gas lets sunlight in but stops a lot of the heat from escaping back into space, so heat builds up. Mercury, by contrast, has almost no air at all, so its heat escapes and its nights are freezing.
(a) Which planet is the hottest in the Solar System, and is it the closest planet to the Sun?
(b) Explain why Venus is hotter than Mercury, even though Mercury is closer to the Sun.
(c) Using this example, explain why distance from the Sun is not the only thing that decides how hot a planet is.
1. A spacecraft sends photos of Saturn's rings back to Earth. Explain how an Australian tracking station such as the one near Canberra helps us receive these photos.
2. Name two outer planets and give one memorable feature of each.
Wrap Up
In one sentence, what was the main idea of this lesson?