Kepler's Laws + Gravity + Key Vocab

Front

What is Kepler's First Law of Planetary Motion?

Back

Planets move in elliptical orbits with the Sun at one focus.

Front

What is Kepler's Second Law of Planetary Motion?

Back

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

Front

What is Kepler's Third Law of Planetary Motion?

Back

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

Front

What is gravity?

Back

A force that attracts two bodies towards each other, proportional to their masses and inversely proportional to the square of the distance between them.

Front

What is eccentricity in relation to an ellipse?

Back

A measure of how much an ellipse deviates from being circular; ranges from 0 (circle) to 1 (parabola).

Front

What are the foci of an ellipse?

Back

Two fixed points located along the major axis of the ellipse, used in the definition of the ellipse.

Front

What is perihelion?

Back

The point in the orbit of a planet where it is closest to the Sun.

Front

What is aphelion?

Back

The point in the orbit of a planet where it is farthest from the Sun.

Front

How does the speed of a planet change in its orbit?

Back

A planet moves faster when it is closer to the Sun (perihelion) and slower when it is farther away (aphelion).

Front

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

Back

Elliptical.