Courses › Computational astrophysics › Module 1: Introduction › Lesson 2
Lesson 2: The Solar System
Eight worlds, four and a half billion years forward
🎯 Objectives
- Recognise which planets have a global magnetic field and which don't
- Read the results of a long-term simulation
- Tell a measured value from a model result
🧪 Exercise
- Simulate Earth and Mars for 4.5 Gyr with dt = 10,000 years.
- Compare each one's percentage of time with a magnetic shield.
- Explain in your own words why that difference matters for an atmosphere.
⚠️ Model limits
- The simulations start from present-day values and run forward: they do not reconstruct the past (for example, the shutdown of Mars's dynamo).
- The model assumes a constant tidal efficiency, so the lengthening of the day and the lunar recession differ from the rates measured today.
- Venus: the model drives it toward synchronous rotation with the Sun (from 243 to ~225 days) because atmospheric tides are off by default; in reality those tides help maintain its slow, retrograde rotation.
📚 References
- Williams & Boggs (2016), Secular tidal changes in lunar orbit and Earth rotation.
- Anderson et al. (2011), The global magnetic field of Mercury from MESSENGER orbital observations.
- Acuña et al. (1999), Global distribution of crustal magnetization discovered by the Mars Global Surveyor.
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