Year 7 Science · Unit 4 · Lesson 16
Extension · Apply Worksheet
Learning Goals
Extension · optional
Touring the planets one by one, out to Uranus and Neptune, goes further than Year 7 asks for, and the planet-by-planet detail is not assessed. One idea here does count: Pluto being reclassified is exactly the kind of evidence-changes-the-model story this unit tests.
True or false? Fix the false ones
Circle T or F. If a statement is false, correct it on the line.
1. Jupiter is the largest planet in the Solar System.
Correct it:
2. Uranus is tipped right over, so it spins on its side.
Correct it:
3. Venus is the closest planet to the Sun.
Correct it:
4. The four outer planets have solid, rocky surfaces you could land on.
Correct it:
5. In 2006 Pluto did not move or shrink; the rule for what counts as a planet changed.
Correct it:
6. Saturn is the only planet known to have liquid water on its surface.
Correct it:
Order the planets: closest to farthest
Number these five planets from 1 (closest to the Sun) to 5 (farthest from the Sun).
| Number | Planet |
|---|---|
| Saturn | |
| Neptune | |
| Jupiter | |
| Mercury | |
| Mars |
Read the data: the hottest planet
Scenario: closer is not always hotter
Is the closest planet always the hottest? Check with Mercury and Venus, with Earth added as a comparison.
| Planet | How far from the Sun (million km) | Air around the planet | Surface temperature |
|---|---|---|---|
| Mercury | 58 | almost none | about 430 °C by day, about −180 °C at night |
| Venus | 108 | a very thick blanket of cloud and gas | about 465 °C, day and night |
| Earth | 150 | a thin layer of air | about 15 °C on average |
Source: rounded standard values. The lesson says only that Venus is hotter than Mercury.
1. How much farther from the Sun is Venus than Mercury?
Difference million km
2. Use Table 1 to explain why Venus is hotter than Mercury, even though Mercury is closer to the Sun.
Cause and effect: how Pluto became a dwarf planet
Fill the two empty boxes. Each box is caused by the one before it, and row 2 carries on from the end of row 1.
3. Priya says: “The closer a planet is to the Sun, the hotter it is.” Use Mercury’s night temperature and Venus’s temperature from Table 1 to test her claim.
Scenario: listening to spacecraft
A spacecraft near Saturn sends photos to Earth as faint radio signals. NASA catches them with giant dishes at only three tracking stations: one at Tidbinbilla near Canberra, one in Spain and one in the United States.
4. At one moment the station in the United States cannot receive the spacecraft’s signal at all. Use the fact that the Earth spins to explain why, and why NASA spreads its three stations around the globe.
5. A museum is building a walk-through tour of the planets, with one sign for the inner planets and one for the outer planets. Write the text for both signs so that visitors can compare the two groups.
True or false
1. True. 2. True. 3. False: Mercury is the closest. 4. False: they are mostly gas and ice, with no solid surface. 5. True. 6. False: Earth is the only planet known to have liquid water on its surface.
Order the planets: closest to farthest
Reading down the table as printed, the correct numbers are 4, 5, 3, 1, 2. In order: Mercury, Mars, Jupiter, Saturn, Neptune. [1 mark]
Read the data: Question 1
108 − 58 = 50 million km. [1 mark]
Question 2
Venus has a very thick blanket of cloud and gas (1) that lets sunlight in but stops heat escaping (1). Mercury has almost no air, so its heat escapes (1). [3 marks]
Cause and effect: how Pluto became a dwarf planet
Box 1: Pluto is found to be small, one of many icy worlds beyond Neptune (1). Box 2: in 2006 astronomers agree a clearer rule: orbit the Sun, be round, clear its path (1). [2 marks]
Question 3
The claim fails: Mercury is closer but falls to about −180 °C at night; Venus stays about 465 °C (1). A planet’s air (how much heat it traps) matters too (1). [2 marks]
Question 4
As the Earth spins, each station is turned away from the spacecraft for part of the day (1); the US station is facing away at that moment (1). Spread around the globe, at least one station can always reach the spacecraft (1). [3 marks]
Question 5
Marking guide: 1 inner four in order; 1 outer four in order; 1 inner: small, rocky, solid surfaces; 1 outer: huge, mostly gas and ice, no solid surface; 1 two correct inner features; 1 two correct outer features (any from the lesson). [6 marks]
Model answer: Inner: Mercury, Venus, Earth, Mars; small, rocky worlds you could stand on. Venus is the hottest; Mars is red, with the tallest known volcano. Outer: Jupiter, Saturn, Uranus, Neptune; huge worlds of gas and ice with no solid surface. Saturn has rings; Neptune is the windiest.
Common error: explaining Venus’s heat by distance alone.