The Apple and the Moon

Ptolemy (date)

150 CE

Copernicus (date)

1543 CE

Kepler (date)

1609 CE

Galileo (date)

1643 CE

Newton (date)

1666 CE

Aristotle (date)

350 BCE

The distance (in meters) that an object near the surface of the earth falls in one second.

4.9 m

Plato (date)

400 BCE

Geocentric

Centered on the Earth

Heliocentric

Centered on the Sun

First published a heliocentric view of the solar system

Copernicus

Who demonstrated that all objects near the surface of the earth fall with equal acceleration.

Galileo

Epicycle (definition)

Presumed, smaller, circular orbit of a planet. The center of which circle moves along a larger circular orbit.

Developed the most complete geocentric model of planetary motion

Ptolemy

They used epicycles to account for retrograde motion of the planets

Ptolemy and Copernicus

Retrograde motion (definintion)

The (apparent) backwards motion of planets against the background of the stars.

1/20 of an inch

The amount that the moon "falls" from its tangential path every second. Calculated by Newton to demonstrate that his Universal Law of Gravity accounted for the motions of both the apple (on earth) and the moon (in the heavens).

Kepler's Third Law of planetary motion

The period of planetary revolution is proportional to the orbital radius.

Kepler's First Law of planetary motion

The planets move in elliptical orbits. The sun at one focus of the ellipse.

Kepler's Second Law of planetary motion

The planets sweep out equal areas in equal time. (Planetary velocities are inversely proportional to the planet's distance to the sun.)

1:60

The ratio of the earth's diameter to the distance of the moon from the earth.