Kepler's Laws

Front

What are Kepler's Laws?

Back

Kepler's Laws describe the motion of planets around the sun, consisting of three laws: 1) The Law of Orbits, 2) The Law of Areas, and 3) The Law of Periods.

Front

What is the shape of a planet's orbit according to Kepler's First Law?

Back

An ellipse.

Front

What does Kepler's Second Law state?

Back

A line segment joining a planet and the sun sweeps out equal areas during equal intervals of time, meaning a planet moves faster when it is closer to the sun.

Front

What is the significance of the foci in an ellipse?

Back

The foci are two fixed points in an ellipse; the sum of the distances from any point on the ellipse to the foci is constant.

Front

What happens to a planet's speed as it moves farther from the sun?

Back

A planet moves slower when it is farthest from the sun.

Front

What is eccentricity in relation to an ellipse?

Back

Eccentricity measures the deviation of an ellipse from being circular; it ranges from 0 (circle) to 1 (parabola).

Front

What is the eccentricity of a circle?

Back

Zero.

Front

What is the relationship between the semi-major axis and the orbital period of a planet?

Back

According to Kepler's Third Law, the square of the orbital period is proportional to the cube of the semi-major axis of its orbit.

Front

Define aphelion.

Back

Aphelion is the point in the orbit of a planet where it is farthest from the sun.

Front

Define perihelion.

Back

Perihelion is the point in the orbit of a planet where it is closest to the sun.