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During his life, Eratosthenes saw how the stars seemed to rotate around the earth. After observing them, he found out the axis of rotation and used that to find how much the earth was tilted compared to its plane of equator.
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This was the year that Eratosthenes calculated the size of the earth, and got about 24,660 miles for the circumference. -
Ptolemy wrote a book that he called Almagest. This was an astronomy textbook and star catalogue, and ended up being Ptolemy's most famous work. This book was used for more than the next thousand years. It taught people who read it how to predict any star's position at any time -
Ptolemy set up a model of the solar system, but it wasn't like the one we know. His has the planets, sun, and stars revolving around the earth. Although we know that his model was wrong, it was used as fact for hundreds of years. Ptolemy also set up a system that predicted the movement of the stars.
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Azophi studied the stars in the Andromeda galaxy and charted them down, putting them in a book for future people to study and learn from. -
Abd al-Rahman al-Sufi, also known as Azophi, was the first person to give a known account of stars that our outside of our on solar system, the Milky Way. This group of stars that he studied came to be known as the Andromeda galaxy.
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By the time Copernicus was born, Ptolemy's theory of the earth being at the center of the solar system had become confusing. This was because many other things were found out about the solar system. Copernicus addressed this problem in his lifetime, saying that the sun was at the center of the solar system.
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It was this year that Copernicus started to write a book that he kept as the basis for his sun-centered system. This book was not published in his lifetime. There were some doubts to his theory, like why things didn't fall to the sun instead of the earth if the earth wasn't the center of the solar system. -
Galileo improved on existing models of telescopes. When he turned telescopes to the skies, he discovered four moons of Jupiter. they were named Lo, Ganymede, Europa, and Callisto. He published a book in 1610 that recorded another finding. Galileo called it a star, but we know his finding today as the planet Neptune.
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By the time Kepler was born, people believed that the planets orbited the sun in perfectly circle orbits. In his life, Kepler proved that the planets moved in elliptical orbits instead. He created a few of what became known as Kepler's planetary laws, and they are now used to calculate not just the movement of planets, but the orbiting of satellites and space stations.
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It was in this year that Kepler wrote the "first public defense of the Copernican System." This was a dangerous move on Kepler's part because Martin Luther derided the theory when he heard about it, and Catholic church thought of the position as heretical. -
Galileo made his first telescope in this year. It was based off of other telescopes around Europe that could magnify objects three times their actual size. But, Galileo's telescope could magnify objects twenty times their actual size. -
Cassini was an astronomer that measured the time it would take the planets Jupiter and Mars to make a rotation. He and another astronomer calculated the distance Mars was from the Earth. This led to others being able to calculate the first dimensions of the solar system.
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Huygens worked on the way light moved, and gave three theories about how we see things. The first theory was that the eye sent out something that reacted with our surroundings, causing us to see things. The second was that our surroundings send out something that reacted with our eyes. The third was that there was something between our surroundings and our eyes that helped us to see the thing around us.
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Definitely one of the most famous scientists, Newton created the laws of gravity and how forces act on one another. This led us to be able to know how all of the planets were held in orbit around the sun, and also how the moons stay in orbit around their planets. From these laws, we also know what we need for our satellites and space stations to stay in orbit around earth and other planets.
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This year, Huygens improved how the lens of the telescope were made, resulting in clearer images. Previously to Huygens looking at Saturn, it was just seen as an elongated blob. Now with his better telescope, he looked at Saturn and could see that it had rings that surrounded it. Although he was not believed at first, some proved his evidence to be true, and Saturn was accepted with rings. -
Halley observed Venus's movements between us and the sun and used those to determine the distance that spans the gap between the earth and the sun. He also measured where the moon was on the meridian and the phase it was in at that time. Although he was working on charting the path of the moon, he was actually hoping that his work would help others to find out what longitude they were at while at sea.
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This was the year that Cassini found the first of four moons of Saturn that he was to find in his lifetime. Lapetus, Rhea, Tethys, and Dione were the names of the four moons. These moons were also known as Louisian Stars, in honor of the French King. -
To any action there is always an opposite and equal reaction; In other words, the actions of two bodies on each other are always equal and always opposite in direction. -
Halley published a book called "A Synopsis of the Astronomy of Comets." In his book, he told about comets that were seen in the years 1456, 1531, 1607 and 1682. These comet sightings were described almost exactly the same, and so had to be the same comet. This led to his prediction of the comet being seen again in 1758. Although he did not live to see the comet swing by, it is now dubbed Halley's comet in his honor.
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