Nicolaus Copernicus was a Polish mathematician and astronomer who developed the heliocentric model of the universe, which placed the Sun, not the Earth, at the center of the universe.

Galileo Galilei used a refracting telescope, which uses lenses to focus light, to make his observations of the heavens.

Kepler's Third Law states that the square of the orbital period of a planet is proportional to the cube of the semi-major axis of its orbit.

Isaac Newton published his laws of motion and universal gravitation in his book Principia Mathematica.

William Herschel discovered the planet Uranus in 1781.

Urbain Le Verrier discovered the planet Neptune in 1846.

Clyde Tombaugh discovered the planet Pluto in 1930.

Voyager 1 was launched in 1977 to study the outer planets of the solar system.

Spitzer Space Telescope was launched in 1990 to study the universe in infrared light.

Chandra X-ray Observatory was launched in 2003 to study the universe in X-ray light.

James Webb Space Telescope was launched in 2018 to study the universe in infrared light.

Square Kilometer Array is the largest radio telescope in the world.

Gran Telescopio Canarias is the largest optical telescope in the world.

Large Hadron Collider is the largest particle accelerator in the world.

National Aeronautics and Space Administration (NASA) is the space agency that is responsible for the United States' space program.