Year 7 Science · Unit 4 · Lesson 16
Master Worksheet
Learning Goals
Reading a planet table
The table below gives a few simple facts about four planets. Use it to answer the questions underneath.
| Planet | Group | Order from the Sun | A memorable feature |
|---|---|---|---|
| Mercury | Inner, rocky | 1st | Smallest planet, closest to the Sun |
| Mars | Inner, rocky | 4th | Red planet, tallest known volcano |
| Jupiter | Outer, giant | 5th | Largest planet, the Great Red Spot |
| Neptune | Outer, giant | 8th | Windiest planet, farthest from the Sun |
(a) Using the table, which planet comes between Mars and Jupiter when counting from the Sun, but is not shown in the table? Explain how you know.
Pluto and the story of changing science
Scenario
For about 76 years, Pluto was taught as the ninth planet. As telescopes improved, scientists discovered that Pluto is very small and is just one of many icy worlds beyond Neptune, some about the same size as Pluto. In 2006 the world's astronomers agreed on a clearer rule: to be a full planet, a world must orbit the Sun, be round, and have cleared its path of other large objects. Pluto orbits the Sun and is round, but it shares its region with many other icy bodies, so it has not cleared its path. Pluto was given the new name dwarf planet.
(a) Explain, in your own words, why Pluto no longer meets the rule for being a full planet.
(b) Pluto did not move or shrink in 2006. So what actually changed? Use the scenario to explain.
(c) Evaluate this statement: "Changing Pluto from a planet to a dwarf planet shows that scientists got it wrong, so we cannot trust science." Do you agree? Justify your answer, using the idea that science updates its ideas when new evidence appears.
Wrap Up
In one sentence, what was the main idea of this lesson?