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Period: 276 BCE to 194 BCE
Eratosthenes
A greek polymath, mathematician, geographer, poet, astronomer, and music theorist
He is best known for being the first person to calculate the circumference of the earth, which he did by using extensive survey results he could access through the library. He was also the first to calculate the tilt of the earth axis with remarkable accuracy. Additionally, he may have calculated the distance from the earth to the sun and invented leap day. Lastly, he was the founder of scientific chronology. -
Period: 100 BCE to 170 BCE
Claudius Ptolemy
A mathematician, astronomer, natural philosopher, geographer, and astrologer.
He wrote several scientific treatises, three of which were of importance to later Byzantine, Islamic, and Western European science. He compiled a star catalog and the earliest surviving tablet of a trigonometric function and established mathematically that an object and its mirror must make equal angles to a mirror. -
Period: Dec 7, 903 to May 25, 986
Abd al-Rahman al-Sufi
Muslim astronomer who worked on translating and expanding Greek astronomical works. He contributed corrections to Ptolemy’s star list and did his own brightness and magnitude estimates which frequently deviated from those in Ptolemy's. He was a major contributor of translation into Arabic of the Hellenistic astronomy that had been centered in Alexandria, Egypt. first attempt to relate the Greek with traditional Arabic star names and constellations. -
Period: Feb 19, 1473 to May 24, 1543
Nicolaus Copernicus
A Renaissance-era mathematician, astronomer, and catholic clergyman who formulated a model of the universe that placed the Sun rather than the Earth at the center of the universe. He also found that the Earth besides orbiting the Sun, also turns once daily on its own axis and that very slow changes in the direction of this axis account for the precession of the equinoxes. -
Period: Dec 14, 1546 to
Tycho Brahe
A Danish nobleman, an astronomer, alchemist, and a writer known for his accurate and comprehensive astronomical observations. He was one of the last major astronomers to work without using a telescope. He devoted many of his efforts to improving the accuracy of the existing types of instruments he did have, such as the sextant and the quadrant. He designed bigger versions of these instruments that allowed him to achieve higher accuracy. -
Period: Feb 15, 1564 to
Galileo Galilei
An Italian astronomer, physicist, and engineer. described as a polymath. He's called the “father of observational astronomy”, the “father of modern physics”, and the “father of modern science”. Galileo studied speed and velocity, gravity and freefall, the principle of relativity, inertia, projectile motion, and also worked in applied science and technology. He invented the thermoscope and various military compasses and used the telescope for scientific observations of celestial objects. -
Period: Dec 27, 1571 to
Johannes Kepler
A German astronomer, mathematician, and astrologer. He is the main figure from the 17th-century scientific revolution, best known for his laws of planetary motion and his books. He eventually became the assistant of astronomer Tycho Brahe in Prague. He did fundamental work in the field of optics, invented an improved version of the refracting telescope. He was also mentioned in the telescopic discoveries of his contemporary Galileo Galilei. -
Period: to
Giovanni Domenico Cassini
He was an Italian mathematician, astronomer, and engineer. He observed and published surface markings on Mars, determined the rotation periods of Mars and Jupiter and discovered four satellites of the planet Saturn and noted the division of the rings of Saturn. He was the first to observe the four moons he called Sidera Lodoicea (the stars of Louis). The Cassini space probe, launched in 1997, was named after him and became the fourth to visit the planet Saturn and the first to orbit the planet. -
Period: to
Christiaan Huygens
He was a Dutch physicist, mathematician, astronomer, and inventor. He was widely regarded as one of the greatest scientists of all time. In physics, he made groundbreaking contributions in optics and mechanics. as an astronomer he is highly known for his studies of the rings of Saturn and his discovery of its moon, Titan. He designed a 50-power refracting telescope with which he discovered that the ring of Saturn was a “thin flat ring, nowhere touching, and inclined to the ecliptic.” -
Period: to
Sir Isaac Newton
He was an English mathematician, physicist, astronomer, theologian, and author who is recognized as one of the most influential scientists. Newton formulated the laws of motion and universal gravitation that formed the dominant scientific viewpoint until it was superseded by the theory of relativity. He built the first practical reflecting telescope and developed a sophisticated theory of colour based on the observations that a prism separates white light into colours of the visible spectrum.