[Leejohnston]

## Kepler’s Laws — Why Orbits Look the Way They Do

### 1. The Key Equation

Orbital period relation:

T² ∝ r³

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### 2. What This Means

The farther a planet is from the Sun:
- the longer its orbit
- the slower it moves

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### 3. Where It Comes From

This relationship emerges from gravity and orbital motion combined.

It was later explained fully by Newton.

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### 4. What This Tells Us

- Orbits are predictable
- Gravity governs motion
- Nature follows simple mathematical rules

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### 5. Real-World Applications

- Planetary motion
- Satellite timing
- Space mission planning

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### 6. Common Misconceptions

- Orbits are perfect circles → false
- Faster orbits mean higher orbits → false

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### Try It Yourself

Why does Mercury orbit much faster than Neptune?