Gravity, Orbits & Kepler’s Laws
📋 What it is
Gravity bends orbits into ellipses; Kepler found planets speed up when closer to the Sun.
🗣️ Coach says
Gravity between masses shapes every orbit. Kepler discovered orbits are ellipses (slightly squashed circles), not perfect circles, and that a planet moves FASTER when nearer the Sun and slower when farther. Gravity plus sideways motion equals a stable orbit.
🧠 Memory hook
Orbits are ellipses; a planet speeds up near the Sun, slows down far away (Kepler).
😂 Giggle
Why did the comet feel popular?
Because every time it showed up, everyone pointed and stared!
😲 Whoa!
Earth actually moves fastest in early January (when we’re closest to the Sun) and slowest in July — the opposite of what many people guess.
✅ Quick check: When does a planet move fastest in its orbit?
Say your answer out loud first — then reveal.
When it’s closest to the Sun — gravity is strongest there, so it speeds up (Kepler’s second law).
Orbital speed rises as distance to the Sun falls.
🧪 Try it! (2 minutes)
Swing a ball on a string; let go and it flies straight — the string was your "gravity".