Unit 3: Forces and energy
The formation of the Solar System — HIA International - Grade 8 Revision Notes & Topical Questions
5 min read 7 parts Lesson 3 of 16 2 quizzes
Lesson summary
The formation of the Solar System — HIA INTERNATIONAL notes: Describe how scientists think the Solar System formed from a nebula and how models and evidence support the hypothesis.Orbits — all planets orbit the Sun in the same direction.Spin — the Sun and all the planets except V…
- Same plane
- Observation
- Our Solar System
- Reason for models
- Limitations
- Contradict
Section 1 of 7Facts about the Solar System
Facts about the Solar System
Orbits
- Orbits all planets orbit the Sun in the same direction.
Spin
- Spin the Sun and all the planets except Venus and Uranus spin on their axes in the same direction.
Moons
- Moons most moons orbit their planets in the same direction as the planets orbit the Sun.
Same plane
- Same plane all the planets orbit in the same plane, so the Solar System looks flat.
Evidence
- Evidence scientists use these facts as evidence for a hypothesis about how the Solar System formed.
Section 2 of 7Nebulae and the birth of stars
Nebulae and the birth of stars
Nebula
Nebula a cloud of dust and gas in space.
Observation
- Observation scientists see distant stars forming from nebulae, some with a flat disc of dust around them.
Example
- Example the Orion Nebula, where stars are being born.
Our Solar System
- Our Solar System scientists think it formed in the same way about 4.6 billion years ago.
Section 3 of 7How gravity builds stars and planets
1
All particles of dust and gas have their own very weak gravity.
2
They pull on each other and stick together, so the total mass increases.
3
More mass gives stronger gravity, which attracts more dust and gas.
4
A small ball forms and gradually grows bigger.
5
If the ball grows beyond a certain size it gets hot enough to become a star; otherwise it becomes a planet.
Time
- Time it takes millions of years to form a star or planet.
Jupiter
- Jupiter scientists think Jupiter almost reached the size needed to be a star.
Section 4 of 7Using models
Model
Model a way of representing something that is difficult to observe directly.
Computers
- Computers scientists put known laws of physics into a program, which predicts that a star forms surrounded by planets.
Reason for models
- Reason for models star formation takes millions of years and cannot be seen in an experiment.
Limitations
- Limitations models are not real, so they may not be accurate.
Section 5 of 7Hypothesis and evidence
Hypothesis
Hypothesis a testable idea.
Support
- Support most facts about the Solar System support the hypothesis.
Contradict
- Contradict the opposite spin of Venus seems to contradict it; contradict means to go against.
Status
- Status it is not proven, because most but not all of the evidence supports it.
Section 6 of 7Key terms
| Term | Meaning |
|---|---|
| Nebula | A cloud of dust and gas in space. |
| Hypothesis | A testable idea or suggested explanation. |
| Model | A way of representing something that is difficult to observe directly. |
| Orbit | The path of an object around a star or planet. |
| Axis | The line about which an object spins. |
| Contradict | To go against. |
Section 7 of 7Exam technique
1
The Solar System formed from a solid lump — it formed from a nebula of dust and gas.
2
Gravity pushes dust apart — gravity pulls the particles together.
3
A theory that has some contradicting evidence is proven — a hypothesis with some contradicting evidence is not proven.
4
All planets spin the same way — Venus and Uranus are exceptions.
Marked practiceQuizzes for this lesson
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