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384 BCE
Aristotle
Aristotle was an early philosopher and astronomer. He started as a student at Plato’s academy and eventually became a teacher there. Aristotle believed that everything revolved around the Earth. This belief was shown by the geocentric model. He thought that since we do not feel the Earth moving that it was stationary. He also said that since objects fall straight down that everything revolves around the Earth. Aristotle knew that the Earth was spherical and proved this through lunar eclipses. -
100
Ptolemy
Ptolemy was an ancient astronomer, mathematician, geographer, and astrologer. He considered the Earth as the center of the universe this was known as the geocentric theory. He made a model of the universe with the Earth in the center also known as the Ptolemaic system. He argued that the Earth is a non-moving sphere at the center of a larger and “celestial” sphere that travels in a perfect cycle carrying all stars, planets, and the sun with it causing the cycle of day and night. -
1473
Copernicus
Copernicus was a mathematician and astronomer. He created the heliocentric theory. Copernican heliocentrism is a model of the universe with the sun in the center. Copernican heliocentrism was created by the one and only Nicolaus Copernicus. His theory wasn’t fully correct but it was closest to the truth of the universe at the time. -
1546
Tycho Brahe
Tycho Brahe was a Danish astronomer. His biggest feat was having the most accurate planetary positions. He paved the way for modern astronomical discoveries. In his life he also found a star in a constellation called Cassiopeia and made what is called the Tychonian Quadrant which is an observational tool. -
1564
Galileo Galilei
Galileo Galilei was a physicist, engineer and astronomer. Like Copernicus he believed in heliocentric universe. He proved the heliocentric theory by discovering the Phases of Venus. One of his other accomplishments was discovering the four largest moons of Jupiter named Callisto, Ganymede, Lo, and Europa. He also made improvements upon the telescope and it was called the Galilean telescope. -
1570
Hans Lippershey
Hans Lippershey was a dutch spectacle maker. He was the first person to apply for a patent on the telescope. Although he was the first to apply for a patent it wasn’t granted because too many people knew about the invention and it was very easily copied. This was the result of two other people claiming they invented the telescope. States General agreed to pay Lippershey nine hundred florins for his invention on the condition that it had to be modified into binoculars. -
1571
Johannes Kepler
Johannes Kepler was an astronomer, mathematician, and astrologer. He is best known for his three laws of planetary movement. Which were the law of eclipses, law of equal areas, and law of harmonies. This means that the planets move in an elliptical orbit around the sun, an imaginary line between the planet and the sun sweeps out equal areas at equal times, and if you square the orbital period it is proportional to the cube of the semi major axis of its orbit. -
Giovanni Cassini
Giovanni Cassini was a mathematician, astronomer, and engineer. He discovered the gaps in Saturn’s rings the gaps were called the Cassini Division. He also discovered the four major moons of Saturn and they were called Iapetus, Rhea, Tethys, and Dione. He also was the first to make accurate measurements of longitude. -
Sir Isaac Newton
Sir Isaac Newton was a mathematician, physicist, astronomer, theologian, and author. He created the three laws of motion and formulated the belief in gravity as a universal force. He also invented the reflecting lenses for smaller telescopes for a better image. Isaac Newton believed that the gravitational force continuously pulls each planet towards the Sun. -
William Hershel
William Herschel was an astronomer most known for discovering the planet Uranus. He also discovered Saturn’s sixth and seventh moon Enceladus and Mimas as well as two of Uranus’ moons named Titania and Oberon. He constructed a larger telescope which was forty feet long but it was too problematic to use. He ended up examining the whole section of sky over Great Britain. He observed over four thousand six hundred and thirty star clusters and nebula and gave the asteroid its name. -
Refracting vs Reflecting Telescopes
The reflecting and refracting telescopes were made to observe the sky and they were different from each other in many ways. For example, the reflecting telescope uses a mirror to put the observations into focus. The refracting telescope depends fully on the lens to gather the light and focus the image. The refracting telescope had issues on focusing all colors to one focal point. The reflecting telescope did not have this issue but it had other issues that over time were solved. -
Percival Lowell
Percival Lowell was a businessman, author, mathematician, and astronomer. He built an observatory in Flagstaff, Arizona to observe Mars. He found what looked like canals on Mars but the canals were disproven by the Mariner 9. Before the end of his death he predicted the existence of Pluto. -
Ejnar Hertzsprung
Ejnar Hertzsprung was a Danish astronomer and chemist. He classified star by color and absolute brightness this classification resulted in something known as spectroscopic parallaxes which is the method for measuring the distances to stars. He created something known as the Hertzsprung-Russell diagram which is basically a scatter plot of the stars. He also established a luminosity scale for a cepheid variable star which is a star that pulses in a predictable cycle. -
Albert Einstein
Albert Einstein was a physicist. He developed the theories of relativity which explained how objects moving at a consistent speed and in a straight line would have time and space linked. He found that space and time were connected in a single continuum called space-time. He also made the discovery that a large object can distort space-time which people feel as gravity. -
Edwin Hubble
Edwin Hubble was an astronomer known for the Hubble sequence which is a system of classification for galaxies. Hubble proved that there are galaxies outside of the Milky Way like the Andromeda Nebula. He also formulated the idea that the galaxies are moving away from each other. His work was revolutionary in the astronomical field. -
Karl Jansky
Karl Jansky was a physicist and radio engineer. He was the first person to discover radio waves being emitted from Milky Way. His discovery eventually developed into radio astronomy. Unfortunately he didn’t further develop radio astronomy. -
John Glenn
John Glenn was an astronaut who was known for orbiting Earth a total of three times. He was the first American to orbit the Earth. Glenn was selected by NASA to be one of the first astronauts in the nation, the people selected were called the Mercury 7. -
Neil Armstrong
Neil Armstrong was the first astronaut to land on the moon on Apollo 11. As many forget before Neil landed on the moon he went aboard Gemini 8 when things went awry and they had to abort the mission. He got lots of recognition for being the first man to walk on the moon. In 1978 he was awarded the Congressional Space Medal of Honor. -
Yuri Gagarin
known as the space race.
Yuri Gagarin was the first person to fly in space. He completed one orbit around Earth and was in space for a total of one hundred and eight minutes. He left Earth in the Soviet Union’s Vostok spacecraft. -
Sputnik
Sputnik was the first satellite to be launched into Earth’s orbit to take pictures. It was launched by the Soviet Union. The Sputnik orbited for three weeks until its battery died. It held very valuable information like the density of the Earth’s atmosphere. The Sputnik launched what is known as the space race. -
The Apollo Program
The Apollo Program was the third space program in the United States. The Apollo program carried out seventeen missions. The missions carried out by this program succeeded on being the first to land people on the moon (Apollo 11). The Apollo Program was extremely important because it brought back samples from the moon to help people understand the moon’s composition and history. The program helped further advance astronomy and knowledge of the universe. -
First Space Shuttle Flight
The First Space Shuttle flight took place on April 12, 1981. The name of the shuttle was Columbia. Columbia brought dozens of astronauts to space over the span of two decades and carried out twenty eight missions. The program was called Space Transportation System and the first space shuttle flight was called STS-1 and carried two people, John Young and Bob Crippen. The first mission was a success and is known as the first space shuttle flight. -
Mars Pathfinder Expedition
Mars Pathfinder expedition was a mission to send a robotic rover to Mars. Mars Pathfinder was launched on December 4, 1996. The mission was successful landing the rover on Mars in the outflow channel on Mars. The rover carried scientific instruments to test the composition of Mars and to study Mars’ atmosphere. The rover accomplished in transmitting a total of 2.3 billion bits of information back to the United States. -
Cassini Orbiter
The Cassini orbiter was launched on October 15, 1997. It was designed to reach Saturn and take accurate measurements, detailed images, and information on the atmosphere. It took seven years before it reached Saturn. The spacecraft was equipped for 27 science investigations. The Cassini orbiter landed on Saturn’s moon called Titan and is the farthest spacecraft landing to date. The Cassini orbiter has expanded the knowledge of Saturn abundantly. -
New Milky Way Map
The new Milky Way map has over 1.7 billion stars plotted on it. This 3D model gives us the best and most detailed view of the Milky Way. This map was a result of the release of data from European Space Agency’s Gaia spacecraft. The map is expected to cause hundreds of discoveries about space.
