• investigated the nature of light, discovering that sunlight is made of light of different colors; the spectrum is, in order from long to short wavelength: red, orange, yellow, green, blue, indigo, violet

• developed a reflecting telescope• Newton's Law of Gravitation describes the gravitational attraction

between objects; the force of their gravitational attraction (F) depends only on their masses and the distance between them, according to the formula F = Gm1m2 / r2. The universal gravitational constant (abbreviated G) is the constant of proportionality in Newton's equation; G is a fundamental constant of nature that determines the strength of the force of the gravitational interaction between objects

Reflecting telescope

gravity

• constructed the first complete astronomical telescope• discovered that the moon, shining with reflected light, had an uneven,

mountainous surface• discovered the four largest satellites of Jupiter, the first satellites of a

planet other than Earth to be detected• observed and studied the oval shape of Saturn and phases of venus• His investigations confirmed his acceptance of the Copernican theory of

the solar system

Galileo’s recordings of Venus's phases

Galileo’s recordings of Jupiter’s moons

• First to correctly explain planetary motion, thereby, becoming founder of celestial mechanics and the first "natural laws" in the modern sense; being universal, verifiable, precise.

• The First Law: The orbit of a planet/comet about the Sun is an ellipse with the Sun's center of mass at one focus

• The Second Law: A line joining a planet/comet and the Sun sweeps out equal areas in equal intervals of time

• The third law: The squares of the periodic times are to each other as the cubes of the mean distances.

Second Law

First law

• Copernicus thought that the planets orbited the Sun, and that the Moon orbited Earth. The Sun, in the center of the universe, did not move, nor did the stars.

• Ptolemy thought that all celestial objects — including the planets, Sun, Moon, and stars — orbited Earth. Earth, in the center of the universe, did not move at all.