Understanding Kepler's Third Law

Which of the following best describes Kepler's Third Law of Planetary Motion?

• The orbit of a planet is an ellipse with the Sun at one of the two foci.

• A line segment joining a planet and the Sun sweeps out equal areas during equal intervals of time.

• The square of the orbital period of a planet is directly proportional to the cube of the semi-major axis of its orbit.

• The gravitational force between two bodies is proportional to the product of their masses and inversely proportional to the square of the distance between them.

If a planet's orbital period is 8 years, what is the approximate length of the semi-major axis of its orbit in astronomical units (AU), according to Kepler's Third Law?

• 2 AU

• 4 AU

• 8 AU

• 16 AU

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NGSS.HS-ESS1-4

Given that the orbital period of Earth is 1 year and its semi-major axis is 1 AU, what would be the orbital period of a planet with a semi-major axis of 4 AU?

• 2 years

• 4 years

• 8 years

• 16 years

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NGSS.HS-ESS1-4

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NGSS.HS-ESS1-4

If a planet's semi-major axis is doubled, by what factor does its orbital period increase?

• 2

• 4

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NGSS.HS-ESS1-4

A planet orbits a star with a semi-major axis of 9 AU. What is the orbital period of the planet in years?

• 9 years

• 18 years

• 27 years

• 81 years

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NGSS.HS-ESS1-4

If a planet's orbital period is 27 years, what is the semi-major axis of its orbit in AU?

• 3 AU

• 9 AU

• 27 AU

• 81 AU

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NGSS.HS-ESS1-4

Which of the following statements is true according to Kepler's Third Law?

• The closer a planet is to the Sun, the longer its orbital period.

• The further a planet is from the Sun, the shorter its orbital period.

• The square of the orbital period is proportional to the cube of the distance from the Sun.

• The orbital period is inversely proportional to the distance from the Sun.

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NGSS.HS-ESS1-4

A planet has an orbital period of 64 years. What is the semi-major axis of its orbit in AU?

• 4 AU

• 8 AU

• 16 AU

• 32 AU

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NGSS.HS-ESS1-4

If a planet's semi-major axis is 1 AU, what is its orbital period?

• 0.5 years

• 1 year

• 2 years

• 4 years

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NGSS.HS-ESS1-4