Kepler's Laws

Front

What are Kepler's Laws of Planetary Motion?

Back

Three laws that describe the motion of planets around the sun: 1) Planets move in elliptical orbits with the sun at one focus. 2) A line segment joining a planet and the sun sweeps out equal areas during equal intervals of time. 3) The square of the orbital period of a planet is proportional to the cube of the semi-major axis of its orbit.

Front

What shape do planets' orbits take according to Kepler's First Law?

Back

Elliptical.

Front

What is the significance of the focal points in an ellipse?

Back

In an ellipse, the sum of the distances from any point on the ellipse to the two focal points is constant.

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 as it orbits the sun?

Back

According to Kepler's Second Law, a planet moves faster when it is closer to the sun and slower when it is farther away.

Front

What does Kepler's Third Law state?

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 the heliocentric model?

Back

A model of the solar system where the sun is at the center and planets orbit around it.

Front

What is the geocentric model?

Back

An outdated model of the solar system where the Earth is at the center and all celestial bodies orbit around it.

Front

What is eccentricity in relation to orbits?

Back

Eccentricity measures how much an orbit deviates from being circular; a value of 0 is a perfect circle, while values closer to 1 indicate more elongated orbits.