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Period: 310 BCE to 230 BCE
Aristarchus of Samos
Aristarchus was the first person to propose a heliocentric model. He also made two kinds of sundials. Aristarchus also made observations on the size of the sun and the moon. -
Period: 92 to 92
Agrippa
The only thing known about Agrippa as an astronomer is that he observed the occultation of a part of the Pleiades. -
Period: 100 to 100
Andronicus of Cyrrhus
Andronicus is best known for designing the Tower of the Winds in Athens. Inside of the tower was a water clock and on the outside was numerous sundials. Andronicus also made a sundial with multiple faces. -
Period: Dec 14, 1546 to
Tycho Brahe
Tycho proposed a new model for the universe. In Tycho's model he claimed that the sun orbits Earth, and the other planets orbit the sun. Tycho also discovered a new star while observing the sky. -
Period: Feb 15, 1564 to
Galileo Galilei
Galileo built an improved telescope and observed numerous things. In his observations were the stars of the Milky Way, the phases of Venus, four of Jupiter's satellites, Saturn's rings, lunar craters, and sunspots. -
Period: Dec 27, 1571 to
Johannes Kepler
Kepler was an assistant for Tycho Brahe. Kepler is most known for his three laws of planetary motion. His laws are:
1. The orbit of a planet about the Sun is an ellipse with the sun at one focus.
2. A line joining a planet and the Sun sweeps out equal areas in equal intervals of time.
3. The square of a planet’s sidereal period around the Sun is directly proportional to the cube of the length of its orbit’s semi-major axis. -
Period: to
Isaac Newton
Newton is best known for creating an equation for the force of gravity. From his equation he was able to account for the trajectories of comets, the tides, and procession of equinoxes. Newton also made the first reflecting telescope and made a theory of color using a prism. -
Period: to
Jacques Cassini
Cassini began working in an observatory in 1712 and the following year he extended the Paris meridian. He was able to determine the Earth's radius and entered into a debate of whether the Earth is prolate spheroid or oblate spheroid. -
Period: to
Karl Ludwig Hencke
Hencke was known for discovering two asteroids. He discovered them from his private observatory in Driesen. He discovered the first on December 8, 1845 and the second on July 1, 1847. The first is named 5 Astraea and the second is 6 Hebe. -
Period: to
Charles Greeley Abbot
Abbot was an astrophysicist who researched the solar constant. From his research he was able to invent things that used solar energy, such as the solar cooker. Abbot also observed eclipses and later became the fifth secretary of the Smithsonian Institute.