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384-322, Aristotle believed in geocentric Universe and that the planets and stars were a perfect sphere but Earth was not, rather Jagged or crooked. He thought the stars must go on forever, since they are circular.
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100-168, Ptolemy created the Ptolemaic system, which stated that the Earth is always stationary, which other planets (Sun, moon, etc.) travel around the Earth in a "Uniform Motion."
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1473-1543, Copernicus mostly believed like Ptolemy, that the Earth held it's center, while the sun, moon etc. revolted around it.
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1546-1601, Tycho helped overturn the belief heliocentric where the sun is in the center. ( Basically the opposite of geocentric ) He believed that Earth was motionless at the center of the universe though, other than moving.
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1570-1619, Hans Lippershey, first person to apply a patent on the telescope, claiming that items could magnify a persons view by looking into the scope. Soon Galileo heard about this and designed a better one the next few days without even seeing one before.
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1571-1630, Johannes Kepler created the 3 laws of planetary motion which laws are stated to be, "1. Planets move in orbits shaped like an ellipse. 2. A line between a planet and the Sun covers equal areas in equal times, and number 3. How long a planet takes to go around the Sun is related to the radius of the planet’s orbit." Kepler's laws of planetary motion is describing the motions of the planets in the solar system.
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1564-1642, Galileo believed most that all things revolted around Earth, and was the first to discover craters on the moon and sunspots. He also discovered the four most massive moons of Jupiter, known as Io, Ganymede, Europa and Callisto.
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1625-1712, Giovanni Cassini discovered four of Saturn's moon, Iapetus, Rhea, Tethys, and Dione, which he called Sidera Lodoicea.
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1643-1724, Sir Isaac Newton was the first to formulate the law of universal gravitation. Basically states that every object in the universe attracts to every other object with a force.
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1738-1822, William Herschel was interested in telescopes when he grew up and created one with a magnifying power of 6,450, which then discovered Uranus and two moons, Titania and Oberon.
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1855-1916, Percival Lowell predicted the existence of a planet beyond Neptune, also initiated a search but ended with the discovery of Pluto.
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1918, the first space shuttle flight to take place in the world. The Shuttle was in Columbia when liftoff, the space shuttle was called STS-1
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1905-1950 Karl Jansky developed the radio telescope. A radio specialized to receive waves from astronomical waves.
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1889-1953, Edwin Hubble discovered 1373 Cincinnati (His only asteroid discovery) which states that, "The X-type asteroid has an extremely inclined, cometary-like orbit of 39 degrees to the ecliptic."
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1879-1955, Albert Einstein created a famous equation known today as E = mc2, shows that energy and mass are interchangeable.
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1957, The first artificial satellite launched called Sputnik-1 made by Mikhail Tikhonravov. At 184 pounds, Sputnik-1 orbited the earth every 90 minutes.
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1921-2016, John Glenn made the first 3 orbits around Earth with friendship 7, a space pod. Unlike Yuri who had made only 1, this was the first time man had orbited 3 times around.
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1873-1967, Ejnar created the luminosity scale of Cepheid Variable stars, a tool to measure intergalactic distances.
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1934-1968, Yuri Gagarin flew out on the first trip to space on April 12, 1961. Lasting 108 Minutes, Yuri circled the Earth. Yuri Gagarin had been the first person in space, and had been a Soviet Hero.
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1930-2012, Neil Armstrong was the first man to ever land on the moon, with Apollo 11, Neil Armstrong had successfully took his first walk on the moon.
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1963-1972, the Apollo Program was created in 1963, and the goal was to make 11 spaceflights and a walk on the moon, and their goal was achieved, Neil Armstrong was the first to ever do that.
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1996, the Mars Pathfinder Expedition began, a rover had been released on mars designed to demonstrate a way to deliver and instrumented lander.
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1997, Cassini Orbiter flew into space, used for taking exact measurements and pictures of different planets etc.
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The difference between refracting and reflecting telescopes is that refracting telescopes use lenses while reflecting uses a mirror that helps eliminate the risk of chromatic aberration.
