Year 7 Science · Unit 4 · Lesson 15
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Learning Goals
Extension · optional
This extension goes beyond the Stage 4 syllabus dot points. The Sun’s layers, sunspots, solar flares and how it makes energy by nuclear fusion go further than Year 7 asks for; nuclear fusion comes back in Year 10 Reactions. Nothing on this sheet is assessed in Year 7, so it is enrichment: do it if you are interested.
Fill the gap: our star
Choose words from the word bank. Each word is used at most once. Two words are not needed: cross them out.
The Sun is a , a giant ball of hot glowing gas called . Its bright surface, the , is the part we see from Earth. About 1.3 Earths could fit inside it. It is about 4.6 years old, which is for a star.
Sort it: sunspot, solar flare or corona?
Write each feature in the correct box. The boxes do not hold the same number of items.
Sunspot
Solar flare
Corona
Order the journey of the Sun’s energy
Number the steps from 1 (first) to 6 (last).
| Order (1–6) | Step |
|---|---|
| The light travels across space to Earth. | |
| The energy slowly works its way outward through the Sun. | |
| A solar panel on a rooftop in Australia captures it. | |
| In the core, hydrogen nuclei are squeezed together very hard. | |
| The energy leaves the photosphere as light and heat. | |
| The nuclei join to make helium, and energy is released. |
1. Overall, four hydrogen nuclei join to make one helium nucleus. How many helium nuclei can be made from 20 hydrogen nuclei? What happens to the small amount of mass that is lost?
Answer helium nuclei
Read the data: counting sunspots
Scenario
An observatory counted the sunspots on the Sun every Monday for six weeks, using a telescope with a strong solar filter. Solar flares often happen near sunspots.
| Week | 1 | 2 | 3 | 4 | 5 | 6 |
|---|---|---|---|---|---|---|
| Sunspots | 14 | 18 | 11 | 5 | 3 | 9 |
Source: made-up results for this worksheet.
2. Draw a column graph of Table 1. Label both axes and give the graph a title.
3. Describe how the number of sunspots changed over the six weeks. Which fact about sunspots from the lesson does this support?
4. In which week were solar flares most likely? Explain, and say what people in Tasmania might see if a flare’s particles reached Earth.
5. Explain how energy made deep in the Sun’s core ends up affecting Earth, both as light and heat and through solar activity.
Fill the gap: our star
star; plasma; photosphere; million; billion; middle-aged. Not used: corona, rock.
Sort it: sunspot, solar flare or corona?
Sunspot: slightly cooler than the gas around it; can be larger than the whole Earth; a dark patch on the photosphere; comes and goes over weeks. Solar flare: a sudden burst of energy; can send particles towards Earth; often happens near sunspots. Corona: the faint outer glow; seen during a total solar eclipse.
Order the journey of the Sun’s energy
Reading down the table as printed, the correct step numbers are 5, 3, 6, 1, 4, 2. In order: squeezed in the core; join to make helium; works outward; leaves the photosphere; travels to Earth; solar panel.
Question 1
20 ÷ 4 = 5 helium nuclei (1). The lost mass becomes energy (1). [2 marks]
Read the data: Question 2
Axes labelled “Week” and “Number of sunspots” with an even scale, and a title (1); six columns at the right heights (1); columns separate and of equal width (1). [3 marks]
Question 3
Rose to 18 in week 2, fell to 3 in week 5, then rose to 9 (1). Supports: sunspots come and go over weeks (1). [2 marks]
Question 4
Week 2 (1): it had the most sunspots (18), and flares often happen near sunspots (1). The particles can make the aurora australis, the southern lights (1). [3 marks]
Question 5
Marking guide: 1 in the core hydrogen joins to make helium (fusion); 1 energy released; 1 works outward, leaves the photosphere as light and heat; 1 warms Earth or lets plants grow; 1 flare particles make auroras; 1 disturbs radio signals and satellites. [6 marks]
Model answer: In the hot core, hydrogen joins to make helium by nuclear fusion, releasing energy. It works outward and leaves the photosphere as light and heat, which cross space to warm Earth and let plants grow. Flares send particles that make auroras and can disturb radio signals and satellites.
Common error: calling a sunspot a hole.