Astronomers of the Past timeline.

Ptolemy was born in Greece about 100 A.D. He made many contributions to geography, mathematics, and astronomy. He spent 14 years in Alexandria, Egypt observing the stars and planets. Ptolemy wrote Almagest, a book that gave a detailed theory involving motion of the Sun, Moon, and the planets. He believed in Hipparchus and Aristotle's theories. Ptolemy addeed the idea that planets move in epicycles. He believed that the planets would turn around their own centers as they revolve around the earth.

Born in 276 BC in Cyrene, Greece and became the head librarian in the city of Alexandria, Egypt. Eratosthenes made a major contribution to astronomy by calculating the circumference of the Earth. At noon during the summer solstice the sun reflected on the bottom of a well in Syene. He concluded that this city must be in a direct line between the sun and the center of the earth. he calculated the angle of the sun's shadow in Alexandria at exactly noon on the same day.

Pythagoras was born in Greece about 560 BC. He was one of the earliest known astronomers. He thought that the unniverse revolved around a fire in the center of the Earth.

Nicalous Copernicus was born in Poland on February 19, 1473. He studied mathematics, astronomy, medicine, and law. He practiced medicine and law for his chuurch for many years, but he never lost his love for astronomy. In 1514 at the age of 40, he wrote a paper challanging the geocentric theory. He agreed with Hipparchus that the planets revolve in perfect circles. He also believed that the planets have epicycles. He introucced the idea that the earth and p;anets revolve around the sun.

Tycho Brahe was born in Denmark in 1546. He studied law, but became interested in astronomy when he observed a solar eclipse in 1560. He read Ptolemy's Almagest and went on to study science in several universities. In 1572 he discovered a nova and five comets that were beyond the Moon's orbit. His findings did not agree with either Ptolemy or Copernicus so he developed his own theory called the Tychonic system.

Galileo Galilei as a young boy hated science becausehe did not believe what was taught. He felt theories needed to be proved before they could be believed. He discovered that mathematics could provide a way to test scientific theories. In 1604 he became interested in astronomy when a Supernova appeared. In 1609 he was introduced to a Dutch toy that mad things look closer than they really were. He designed a bigger one and turned it toward the sky. He foundout that the planets circle the Sun.

Johannes Kepler was born in Germany. He sudied astronomy under Tycho Brahe and supported most of the theories developed by Copernicus. He observed the orbit of planets and was the first to accurately determine their position and how they orbited the sun. He Developed three laws regarding planetary motion.

Sir Isaac Newton is often noted as the greatest scientific genius of all time because he made major contributins to every area of science known during his time. In the field of astronomy, Newton is best known for his laws of motion and gravity. People already knew that objects fell to the ground, but they didn't know why it happend. He explained that there was a force called gravity that pulled objects toward the earth. He developed the theory of gravitational pull.

Sir William Herschel was a music teacher but spent his spare time studying astronomy and building telescopes. He construucted the largest telescopes of his time using them to observe the six known planets: Mars, Mercury, Venus, Earth, Jupiter, and Saturn. In 1781 he descoverd a new planet. He named it after the king of England at that time. In 1782 he contructed an even larger telescope and found that the new planet had 2 moons! The name of the planet never really stuck.It was soon named Uranus.

Eudoxus was born in greece around 408 BC. He was a scholar interested in the motions of celestial bodies (stars,planets,and moons).He was the first person to develop the theory that the stars and planets are spheres that move in concentric circles around the Earth.

Aristotle was born in Greece in 384 BC. When he was 17 he went to Atthens to study under Plato. During that time he began to observe nature, record wht he found, and form theories about how nature worked. He explained many ideas in astronomy. He agreed with the geocentric theory. But he did not believe i the theory of the planets revolved in circles. His observations led him to belive that the planets revolved in oval-shaped orbits. He is one of the most famous a respected thinkers in the world.

Hipparchus was born about 190 BC, in Nicaea, Turkey. He was one of the greatest early astronomersand is known as the Father of Systematic Astronomy. He belived the the Earth was the center of the Universe.and that all other celestial bodies moved around it in perfect circles. He catalouged ve 850 stars and kept a record of their small but important yearly movements in the sky. He found better ways of determining the distances and diameters of the Sun and Moon.