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322 BCE
Aristotle
Aristotle, an Ancient Greek Philosopher believed in the idea of geocentricity. This theory stated that Earth was the center of the universe and that everything revolved around it. He was one of the the first to declare that earth was a sphere. He based this theory off of Earth's shadow and the placements of constellations in sky. Aristotle also created his own model of the geocentric universe. -
168
Ptolemy
Similar to Aristotle, Ptolemy believed in a geocentric universe. He is known for creating the Ptolemaic system. This system stated that Earth was the center of the universe and that the other planets revolved around it in an epicyclic circle. The world epicyclic is used to describe the gear like motion of the planets. -
1543
Copernicus
Polish scientist, Nicholas Copernicus was the first to suggest the theory of heliocentrism. He believed that Earth and the other planets revolved around the sun. He proposed a model of his heliocentric universe that was not completely correct, but became the basis of what we now know as the universe. -
Tycho Brahe
Tycho Brahe, a Danish astronomer had many accomplishments in that astronomic field. He discovered evidence from a supernova that proved that the "heavens" change. After studying the stars, he proposes his own theory that the sun and moon orbited the Earth, but the other planets revolved around the sun. -
Hans Lippershey
After much controversy Hans Lippershey was credited with the invention of the telescope. His invention magnified things by about 3 times. -
Johannes Kepler
Johhanes Kepler created the Laws of Planetary Motion. His first law depicted how two planets moved elliptically or in an oval. His second law stated that as planets moved further away from away from the sun it moved slower. The last law that he created told that the time that a planet takes to orbit the sun is dependent on how far apart they are. -
Galileo
Astronomer Galileo Galilei believed in Copernicus's system of heliocentrism. He is known for many things including greatly improving on Lippershey's telescope. With this new telescope he discovered Jupiter's moons Io, Ganymede, Europa, and Callisto. These would later become known as the Galilean Moons. Galileo was also the first to notice the moon's craters. -
Giovanni Cassini
Giovanni Cassini is famous for many things including the discovery of Saturn's moons. He figured out an estimation of the solar systems dimensions as well as the first accurate lines of longitude. He also discovered the Cassini Division in Saturn which is a black streak in the ring, and the difference in atmospheric rotation on Jupiter. He also has partial credit of discovering Jupiter's Great Red Spot. -
Sir Issac Newton
Issac Newton is famous for creating the Three Laws of Motion. He discovered the law of gravity which says that two things move closer the gravitational attraction increases and when they move further away it decreases. This law helped astronomers understand many things in the universe including why planets revolve around the sun and why they are round. -
William Herschel
William Herschel was best known for his discovery of the planet Uranus and many moons. He created a 40 foot telescope, but mainly used his 20 foot one. With his telescope he found two of Saturn's moons. He also discovered the color spectrum and found which color correlates to which temperature. One of the things he discovered with the color spectrum was the concept of infrared radiation. This was how the color just past red was higher than light in his spectrum. -
Percival Lowell
American Astronomer Percival Lowell was the founder of the Lowell Observatory in Flagstaff, Arizona. At his observatory he believed to have made the discovery of canals on Mars. If he had been correct, it would o proved that other life could live on Mars. His theory was eventually proven incorrect, along with his beliefs that he could see the features of Venus. He was also convinced that there was another planet just waiting or him to discover. This eventually led to the discovery of Pluto. -
Karl Jansky
Karl Jansky discovered a radio signal coming from outer space. It came from the center of the milky way. He also found signals from thunderstorms. -
Edwin Hubble
Edwin Hubble was a famous astronomer from the 1900's. He discovered an entire new universe outside of the Milky Way. Hubble found a way to classify the shapes of different galaxies. He also proved that the galaxies are expanding. Because of his important work NASA named the Hubble Telescope after him. -
Albert Einstein
Scientist Albert Einstein was very famous for many things including his special theory of relativity. One of his theory's stated that the laws of physics were always the same. The second stated that the speed of light also stayed the same. He predicted that starlight from the sun could be bent and figured out why planet's orbits varied. -
Sputnik
On October 4th, 1957 Germany launched the first satellite into space. This satellite is known as Sputnik. It was small, only the size of a beach ball and made a full elliptical path around Earth in only about 98 minutes. -
Yuri Gagarin
Yuri Gargarin was the first person in space. The Soviet Union launched him into space on April, 12 1961. He made little over a full orbit around Earth in about 108 minutes. -
Ejnar Hertzsprung
Ejnar Hertzsprung was a Danish astronomer who developed many important things that we now about the stars today. He discovered the luminosity scale that we use to tell the distance between celestial things. He also proved the existance of dwarf and giant stars -
The Apollo Program
This was a program made to land Americans successfully on the moon. It had six spacecrafts that landed on the moon. They discovered many new things that revolutionized Astronomy as we know it all throughout 11 flights into space. -
First Space Shuttle Flight
On April 12, 1981 the first space shuttle, the Columbia was launched into space. This was so important because space shuttles were reusable and could venture into space multiple times.The first trip that the Columbia made into space was just to see how it worked. It ended up flying into space 28 times before it burned during re-entry into earth and killed the seven members on board. -
Mars Pathfinder Expedition
The Mars Pathfinder was first launched on December 4th, 1996 and landed on Mars on July 4th, 1997. It provided many new discoveries about the planet, as well as multiple pictures. Because of this expedition we now know about the atmosphere, geology, and climate on Mars. -
Cassini Orbiter
The Cassini Orbiter was launched into space on the Cassini-Huygens space craft. The space craft landed on Saturn and launched the Cassini Orbiter. Over a span of 20 years the Cassini made 294 orbits around Saturn and took 453,048 pictures. -
Neil Armstrong
Neil Armstrong was the first man to walk on the moon. He and his crew flew launched the Apollo 11 on July 16, 1969 and landed on the moon on on July 24, 1969. He said the iconic phrase "That's one small step for man and one huge leap for mankind". -
John Glenn
Astronaut John Glenn was the first American to orbit the Earth. He was launched into space on February 20, 1969. Glenn circled the Earth three times. He landed back on Earth only five hours after being launched. He eventually was launched back into space at age 77 becoming the oldest person in space. -
Bedin 1 Galaxy
Very recently a new galaxy was discovered. Located only about only 30 million lightyears away, this galaxy nicknamed Bedin 1 was discovered by the Hubble Telescope. It is very small and faint, making it very hard to see. It is classified as a dwarf spheroidal galaxy. This means that it is small, has low luminosity, and is lacking in older objects. -
Reflecting vs. Refracting Telescopes
While reflecting telescopes use mirrors to gather light refracting telescopes use lenses. In a refracting telescope after light enters through a lens it is magnified by lenses in the eyepiece. In a reflecting telescope light enters a hole in the telescope and travels until it hits a mirror. It then bounces back off another mirror which sends it to the eyepiece where you can see it.
