# Famous Names in Astronomy

**Albert** **Einstein** – German-American physicist. Einstein is primarily remembered for his *Theory of Relativity*, developed from 1905-1915. This theory was the first significant correction to Isaac Newton’s *Theory of Gravitation* in 250 years. 100 years after the theory was first developed, scientists are still doing experiments to confirm Einstein’s predictions.

**Aristarchus** **of** **Samos** – c. 250 BC. Greek astronomer and mathematician who presented the first known model of the solar system with the Sun in the center of the cosmos.

**Aristotle** – c. 350 BC. Greek philosopher and scientist known for championing the Earth-centered model of the solar system.

**Carl** **Sagan** – American astronomer and scientist. Known for championing space exploration, particularly probes to the outer planets. Creator and host of the original *Cosmos* TV series in the 1980’s.

**Copernicus** – c. 1525. Polish astronomer and mathematician. Known for the redevelopment of the heliocentric (Sun-centered) theory of the solar system. Published his theory posthumously without proving it. Theory was later shown to be true by Galileo.

**Eratosthenes** – c. 225 BC. Greek mathematician and astronomer. Known for measuring the circumference of the Earth, distance to the Moon, etc.

**Galileo** **Galilei** – c. 1610. Italian astronomer, inventor, and mathematician. Known for inventing the first practical astronomical telescope, mapping the Moon, and proving that the geocentric (Earth-centered) model of the solar system was wrong.

**Gerard** **Kuiper** – Dutch-American astronomer. Along with Kenneth Edgeworth, Kuiper is known for predicting a belt of icy comets located beyond the orbit of Pluto.

**Isaac** **Newton** – c. 1665. English physicist and mathematician. Inventor of the reflector telescope, theory of gravitation, particle theory of light, and along with Gottfried Leibnitz the inventor of calculus.

**Johannes** **Kepler** – c. 1600. Kepler was the assistant of the Dutch astronomer Tycho Brahe. Kepler inherited all of Kepler’s scientific work and used Tycho’s data to prove that all planets orbited the Sun in elliptical orbits. Known for the three laws of planetary motion.

**John** **Packard** – c. 1900. American physics teacher. Known for the invention of the *Packard Apparatus*, a slanted table which allowed students to track the path of a rolling marble and calculate the gravitational constant of the Earth.

**Pythagoras** – c. 520 BC. Greek mathematician. Known for the Pythagorean Theorem and the study of geometry and numbers.

**Robert** **Hooke** – c. 1665. English scientist and inventor. A rival of Isaac Newton and inventor of *Hooke’s Pendulum* used to prove that only gravity and inertia are necessary to create an elliptical orbit.

**Tycho** **Brahe** – c. 1575. Danish nobleman and astronomer. Known as the most accurate astronomer in the pre-telescope era. Tycho built his own observatory and designed and built his own instruments which enabled him to make more accurate observations than anyone before him. Tycho’s many years of observational data made it possible for Kepler to develop his *Laws of Planetary Motion* after Tycho’s death.