Early Astronomy
Astronomy is a science that studies the Universe. It deals with the properties of objects in space and the laws under which the universe operates. Astronomy was developed originally by the Greeks through the basics of trigonometry, mathematics and geometry. Though astronomy and what is known about it has evolved since then, the Greeks were the ones who gave us the knowledge that began this field of study
Geocentric ModelThe Greeks held a geocentric view. They thought that the Earth was a sphere which stayed motionless at the center of the universe and that the known planets and sun orbited it. They believed that beyond the planets lied a transparent and hollow sphere on which the stars traveled daily around the Earth. This space was called the celestial sphere
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Heliocentric ModelAristarchus was the first Greek to believe in a sun centered or heliocentric universe. In this model, the Earth and other planets orbited the sun. He used geometry to calculate distances from the Earth to the sun and moon to the Earth. He was even able to use these distances to calculate the size of the sun and moon. His calculations however were not accurate and did not give a real idea of the size and distances between the sun, moon, and earth.
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Birth of Modern Astronomy
The development of modern astronomy came about after breaking away from previously held philosophical and religious views. New ideas emerged that dictated the governing of the Universe by natural laws. There were scientists who worked to uncover these laws and come closer to the truth beyond Earth.
CopernicusCopernicus was the first to claim that the Earth was a planet which rotated in a sun centered solar system. He said the earth and planets rotated with a circular motion, which is a claim that didn't explain why the planets strayed from the predicted positions.
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BraheBrahe was highly interested in the observations of the solar system. He built an observatory and designed instruments which he used to measure and locate the positions of the heavenly bodies. His observations were the most precise up to that points and became later useful by other scientists.
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KeplerKepler preceded after Brahe and with his solid mathematical skills and faith in the accuracy of Brahe's observations, he was able to discover the three laws of planetary motion. He saw that the planets orbited in an elliptical path around the sun. He also found that planets revolve and sweep out equal areas in equal time intervals. He also developed that the orbital period is proportional to the cubed mean distance to the sun.
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GalileoGalileo had his most important contributions result from the development of the telescope. Using his telescope, he was able to make many observations of the behavior of moving objects. Some of his observations included the surface of the moon, and dark regions on the sun called sun spots.
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NewtonOf the five scientists described, Newton and his discoveries were of the most influential. By the age of 23, he described a force that extends from the Earth into space and holds the moon in orbit around the Earth. This is called the theory of Universal gravitation. According to him every body in the universe attracts every other body with a force force directly proportional to their masses and inversely proportional to the square of the distances between their centers of mass.
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