How Planets Move

Students follow the history from Copernicus and Tycho Brahe to Kepler's three laws of planetary motion, then test those laws at Mercury, Earth, Mars, Jupiter, Neptune and Pluto.

Grades 5-8About 15 minutes of narrated flight, plus discussion stops7 stops

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What students will see and do

Students fly from the Sun out through the planets to Pluto while Aetherion explains elliptical orbits, changing orbital speed and the link between distance and the length of a year. The class pauses at Mars, Jupiter and Pluto to discuss trusting data, calculate a year with Kepler's third law, and explain the Neptune-Pluto resonance.

Learning objectives

• Describe a planet's orbit as an ellipse with the Sun at one focus, and draw one using two pins and a loop of string.
• Explain why a planet moves faster when it is closer to the Sun, using Kepler's second law of equal areas.
• Use Kepler's third law (period squared equals distance cubed, in Earth years and Earth distances) to estimate the length of a planet's year.
• Explain how careful measurements led to the discovery of Neptune and to the replacement of circular orbits with ellipses.

NGSS connections

Stops on this journey

1. Who Sits at the Center?
2. Kepler and the Shape of Mars (discussion stop)
3. Faster When Closer
4. Mercury, the Fastest Runner
5. The Law of Years (discussion stop)
6. The Planet Found with Math
7. Pluto's Strange Dance (discussion stop)

Vocabulary

• orbit
• ellipse
• focus
• eccentricity
• orbital period
• retrograde motion
• resonance
• astronomical unit