PHYSICS · Stage 9 · Chapter 15: The Earth in Space (Universe and Stars)
Physics 15.5 Chapter 15 Review: The Earth in Space
5 min read 6 parts Lesson 5 of 6
Lesson summary
Physics 15.5 Chapter 15 Review: The Earth in Space — Alhussan International Academy — Physics (Stages 7–9) notes: Summarise Chapter 15 on the Moon's formation, asteroid impacts, the origin and age of the Universe, the life cycle of stars and the use of models and data.Theia — In …
- Prediction
- Crater model
- Limits of the model
- Computer simulations
- Reliability
- Cosmic calendar
Section 1 of 6The Moon's formation
- Theia
- In the giant-impact story, the molten iron cores of Theia and the Earth merged into the Earth's present core.
- Prediction
- Some of the Moon's material should match the Earth's and some should differ because it came from Theia.
- Testing
- Analysis of Moon rock can support or challenge the hypothesis.
Section 2 of 6Impacts and models
- Tunguska
- An asteroid hit this remote region of Russia in 1908 and flattened about 80 million trees.
- Crater model
- A marble dropped into flour transfers its kinetic energy to the flour, which moves to form a crater.
- Changing the height or mass of the marble changes the crater size.
- Students can test variables safely.
- Limits of the model
- Flour is not rock and the marble does not move at asteroid speeds, so the model is only qualitative.
- Computer simulations
- Simulations of the giant impact are checked against evidence from Moon rocks.
Section 3 of 6Using data sources
- Reliability
- Data from reputable science books and peer-reviewed sources are more reliable than a table in a magazine.
- Checking
- Check data against two or more reliable sources.
Section 4 of 6The age and size of the Universe
- Expansion
- The Universe has been expanding for about 14 billion years.
- Cosmic calendar
- If the history of the Universe is 1 year, the Earth forms in early September and the dinosaurs lived in late December.
- Observable limit
- Light has been travelling for at most the age of the Universe, so the maximum distance we can see is about 13.8 billion light years.
Section 5 of 6Stars and their life cycles
- Sun-like stars
- Nebula, main sequence, red giant, planetary nebula, white dwarf, black dwarf.
- Massive stars
- Nebula, main sequence, red supergiant, supernova, neutron star or black hole.
- Elements
- Heavy elements form only in supernovae.
Section 6 of 6Evaluating models
- Useful model
- It makes predictions that can be tested.
- Evaluating
- Name a strength and a limitation of each model and state how the evidence supports it.
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