According to one of Kepler's laws, a planet is moving fastest in its orbit when it is at

The fact that Earth's seasons are not of equal length (summer is a few days longer than winter), and our knowledge of Kepler's second law, allows us to predict that

The Moon makes one complete circuit around the Earth in about a month. What kind of motion is being described by the Moon?

Sunspots seem to move across the face of the Sun in a matter of days. What kind of spinning motion is the Sun undergoing?

A planet at perihelion is

According to Kepler's second law, in equal times the orbit of each planet sweeps out equal areas. Combined with Kepler's first law, this results in planets that

When a superior planet is exactly 180 degrees from the Sun in the sky, astronomers say it is at

The time it takes a planet to complete one orbit around the Sun is called its

Kepler found that the orbits of the planets were not perfect circles, but rather ____.

Which orbit has the greatest eccentricity?

Which orbit has the largest aphelion?

Which orbit has an aphelion and perihelion that are equal?

Which orbit has an eccentricity nearest zero (0)?

Kepler's _____ law says that the planets orbit the Sun in ellipses, with the Sun at one focus.

Kepler's _____ law says that the line joining the Sun and a planet sweeps equal areas in equal times.

Kepler's _____ law says that the square of the period of revolution is proportional to the cube of the planet's average distance from the Sun.

This Greek philosopher (around 350 B.C.) thought that the Earth was at the center of the universe.

This 16th century Polish astronomer became famous for his theory that the Sun was at the center of the universe and that the Earth moved.

This man calculated the correct size of the Earth in about 250 B.C.

This 19th century French physicist used a pendulum to prove that the Earth moves.

In the early 17th century, this man helped to prove the heliocentric theory by using a telescope to discover four large moons around Jupiter and the phases of Venus.

This mathematician used Tycho's observations of the planets to develop his own "Laws of Planetary Motion" in the early 17th century.

In the 17th century this great scientist discovered the "Laws" that describe gravity. He was born the same year the Galileo died.

This 2nd century astronomer used an Earth-centered model with circles-on-circles (epicycles) to explain the motion of the planets.

This 16th century Danish observer of the planets lost part of his nose in a sword fight.

Newton's first law is also known as the law of _____.

Newton's _____ law can be written: F = ma.

Newton's _____ law says that for every action there is an equal and opposite reaction.

Newton's _____ law says that things continue moving in a straight line at a constant speed unless acted on by an outside force.