Course: 🔷 Separate Physics only | Tier: Foundation + Higher (HT parts marked) | Time: about 60 minutes (you can split it into two 30-minute sessions)
✏️ You need: your exercise book, a pen and a coloured pen for corrections. Work through the steps in order. Write every answer before you open it.
🗺️ Your route through this page
Step 1 Rate yourself (3 min) → Step 2 Watch, learn and check – 5 chunks (35 min) → Step 3 Exam questions (12 min) → Step 4 6-mark answer (8 min) → Step 5 Review (2 min)
🪐 Solar System → ⭐ how stars are born → 🔄 life cycle of stars → 🛰️ orbits → 🌌 red-shift and the Big Bang
Step 1 – Rate yourself 🚦
Copy this table into your book. Give each statement a colour now: 🔴 I can’t do this yet · 🟠 I’m not sure · 🟢 I can do this. You’ll rate yourself again at the end.
| I can… | Start | End |
|---|---|---|
| describe what is in our Solar System | ||
| describe how a star forms and why it is stable | ||
| describe the life cycle of a star like the Sun and a star much bigger than the Sun | ||
| explain where the elements come from | ||
| explain how gravity keeps planets and satellites in orbit | ||
| explain what red-shift tells us, and describe the Big Bang theory |
Step 2 – Watch, learn and check 🎬📖
Do each chunk in order:
1. 🎬 Watch the video and write 3 key facts in your book.
2. 📖 Read the notes.
3. ✅ Answer the quick check without looking back. Correct any mistakes in coloured pen.
Videos by Freesciencelessons (YouTube). If a video won’t play on your network, just read the notes – they cover everything you need.
Chunk A: Our Solar System 🪐
🎬 Watch: The Solar System
📖 Read:
- Our Solar System has one star (the Sun), 8 planets, dwarf planets (like Pluto), moons (natural satellites) and artificial satellites.
- Our Solar System is a tiny part of a galaxy called the Milky Way. There are billions of galaxies in the universe.
- The Sun formed from a nebula – a cloud of dust and gas – pulled together by gravity.
✅ Quick check A
1. What is the name of our galaxy?
2. What is a moon?
3. What force pulled the nebula together to form the Sun?
Show answers
1. The Milky Way
2. A natural satellite that orbits a planet
3. Gravity
Chunk B: How a star is born and why it is stable ⭐
🎬 Watch: Lifecycle of Stars. This video covers Chunks B and C. While you watch, start a flow chart in your book with two paths: one for a star like the Sun, one for a much bigger star.
📖 Read:
- Gravity pulls a nebula together. It gets denser and hotter and becomes a protostar.
- When it is hot enough, hydrogen nuclei fuse to make helium, releasing huge amounts of energy. It is now a main sequence star.
- A main sequence star is stable because two forces are balanced: gravity pulling inwards and pressure from fusion energy pushing outwards. Stars stay like this for billions of years.
✅ Quick check B
1. What is the stage between a nebula and a main sequence star?
2. Which process releases energy in a star?
3. Name the two forces that are balanced in a main sequence star.
Show answers
1. A protostar
2. Nuclear fusion (of hydrogen into helium)
3. Gravity (inwards) and outward pressure from fusion energy
Chunk C: The life cycle of stars 🔄
🎬 Watch: no new video – use the Lifecycle of Stars video from Chunk B. Finish your flow chart, then check it against the table below.
📖 Read: what happens after the main sequence depends on the size (mass) of the star.
| A star about the same size as the Sun | A star much bigger than the Sun |
|---|---|
| nebula | nebula |
| protostar | protostar |
| main sequence star | main sequence star |
| red giant | red super giant |
| white dwarf | supernova 💥 |
| black dwarf | neutron star or black hole |
🧪 Where elements come from: fusion in stars makes elements up to iron. Elements heavier than iron (like gold) are made in a supernova. The explosion spreads the elements through the universe – the atoms in your body were made in stars!
✅ Quick check C
1. What does a star like the Sun become after the red giant stage?
2. What two things can be left after a supernova?
3. Where are elements heavier than iron made?
Show answers
1. A white dwarf (which cools to a black dwarf)
2. A neutron star or a black hole
3. In a supernova
Chunk D: Orbits 🛰️
🎬 Watch: Orbital Motion
📖 Read:
- Gravity keeps planets orbiting the Sun, and keeps moons and artificial satellites orbiting planets.
- Orbits are (almost) circular.
- (HT) An object in a circular orbit moves at a constant speed but its velocity is changing, because its direction is always changing. So it is accelerating towards the centre.
- (HT) A satellite in a smaller orbit must move faster to stay in orbit, because gravity is stronger closer to the planet.
✅ Quick check D
1. What force keeps the Moon in orbit around the Earth?
2. (HT) Why is a satellite in a circular orbit accelerating, even at a constant speed?
Show answers
1. Gravity
2. Its direction is always changing, so its velocity is changing – and a change in velocity is an acceleration.
Chunk E: Red-shift and the Big Bang 🌌
🎬 Watch: Red-Shift
📖 Read:
- Light from distant galaxies is red-shifted – its wavelength has increased, moving it towards the red end of the spectrum.
- This shows galaxies are moving away from us. The further away a galaxy is, the bigger its red-shift, so the faster it is moving away.
- So the universe is expanding. This is evidence for the Big Bang theory: the universe began from a very small region that was extremely hot and dense.
- Since 1998, observations suggest distant galaxies are moving away faster and faster. There is still much we don’t understand, such as dark mass and dark energy.
✅ Quick check E
1. What happens to the wavelength of light from a galaxy moving away from us?
2. What does it mean if a galaxy has a bigger red-shift?
3. What does red-shift tell us about the universe?
Show answers
1. It increases (it is red-shifted)
2. It is further away and moving away faster
3. The universe is expanding
Step 3 – Exam questions ✏️
Answer in full sentences. The marks tell you how many points to make. The questions follow the same order as the chunks. Mark your work in coloured pen.
Q1 (Chunk B) Name the force that pulls a nebula together to form a star. [1 mark]
Mark scheme
gravity (1)
Q2 (Chunk B) Explain why a main sequence star stays the same size for a long time. [2 marks]
Mark scheme
gravity pulls inwards (1)
this is balanced by the outward pressure from the energy released by fusion (1)
Q3 (Chunk C) Put these stages of a Sun-sized star in order: red giant · protostar · white dwarf · main sequence star. [2 marks]
Mark scheme
protostar → main sequence star → red giant → white dwarf
all correct (2); two in the right place (1)
Q4 (Chunk C) Gold is heavier than iron. Where was the gold on Earth made? [1 mark]
Mark scheme
in a supernova (the explosion of a massive star) (1)
Q5 (HT) (Chunk D) Satellite X orbits closer to the Earth than satellite Y. Which one travels faster? Explain why. [2 marks]
Mark scheme
X (1)
gravity is stronger closer to the Earth, so it must move faster to stay in orbit (1)
Q6 (Chunk E) Scientists observe that light from distant galaxies is red-shifted. Explain how this supports the Big Bang theory. [3 marks]
Mark scheme
red-shift shows galaxies are moving away from us (1)
more distant galaxies are moving away faster / the universe is expanding (1)
so the universe must once have been very small, hot and dense (1)
Step 4 – Write a 6-mark answer 📝
Q7 Describe the life cycle of a star that is much more massive than the Sun. [6 marks]
🧩 Planning frame – use your flow chart from Chunks B and C, and these sentence starters:
1. “The star starts as a nebula, which…”
2. “Gravity pulls it together to form a…”
3. “When it is hot enough, … starts. This is a main sequence star, which is stable because…”
4. “When the hydrogen runs out, it becomes a…”
5. “It then explodes as a…, which makes…”
6. “Finally, it leaves behind a… or a…”
Model answer and mark scheme
Model answer: The star starts as a nebula, which is a cloud of dust and gas. Gravity pulls the dust and gas together to form a protostar, which gets hotter and denser. When it is hot enough, nuclear fusion of hydrogen into helium starts. This is a main sequence star, which is stable because the inward force of gravity is balanced by the outward pressure from fusion energy. When the hydrogen runs out, the star swells to become a red super giant. It then explodes as a supernova, which makes elements heavier than iron and spreads them through the universe. Finally, it leaves behind a neutron star or, if it is massive enough, a black hole.
Level 3 (5–6): all stages in the correct order, with reasons (gravity, fusion, balance). Level 2 (3–4): most stages in order, some reasons. Level 1 (1–2): some stages named.
Step 5 – Review 🔁
1. Go back to your Step 1 table and fill in the End column.
2. For anything still 🔴 or 🟠, re-watch that chunk’s video, then write one question to ask your teacher.
3. Write down your score for Step 3 (out of 11) and Step 4 (out of 6).
🚀 What next?
Still 🔴? → Fill the gaps: Space · Draw the Space diagrams
Mostly 🟢? → Space quiz · Space test (Foundation) · Space test (Higher)
Back to the Space topic page
