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322 BCE
Aristotle
Aristotle was a Greek philosopher known for being one of the Fathers of Western Philosophy. He lived from 384 to 322 BC. He contributed to the theory of a geocentric Earth, and he also studied eclipses, and phases of the moon. -
168
Ptolemy
Ptolemy was a Greco-Roman philosopher, astronomer, and mathematician. He contributed to astronomy, math, arithmetic, geography, and astrology. He was one of the first major mathematician to consider Earth at the center of the solar system, also called geocentric Earth. -
1543
Copernicus
Copernicus was a mathematician that lived in the Renaissance-era. He one of the first and most well-known astronomers to create a model of the sun at the center of the solar system, a heliocentric theory rather than a geocentric one. -
Tycho Brahe
Tycho Brahe was a Danish astronomer and writer. He was most known for helping overturn geocentric belief in favor of the heliocentric theory. He also had a weird mustache and a peculiar nose. -
Refracting Telescope
The Refracting Telescope was one of the earliest telescopes, invented in 1608, and credited to Hans Lippershey, Zacharias Janssen, and Jacob Metius. It is an optical telescope that uses its lens to form an objective. The refracting is different from a reflecting telescope because the latter allows larger views and apertures. -
Hans Lippershey
Hans Lippershey was a Dutch eyeglass maker who was believed to have invented the first telescope and compound microscope. He was credited with the invention of the telescope because he was the first to try to receive a patent for it. -
Johannes Kepler
Johannes Kepler was a German scientist, mathematician, and astronomer. He is best known for his laws of planetary motion, three scientific laws describing how each planet revolves around the sun. He also first worked under Tycho Brahe. -
Galileo
Galileo Galilei was an Italian astronomer best known for inventing the telescope to observe the sky and stars, and Earth. He invented many things, and also contributed to the heliocentric theory. -
Reflecting Telecope
The Reflecting Telescope is an optical telescope that uses groups of mirrors to reflect light and form images. It is credited to Issac Newton, who had the first design for a reflecting telescope. The difference between the refracting and the reflecting telescope is that the refracting telescope uses lens to gather light and form an image, while the reflecting telescope uses mirrors. -
Giovanni Cassini
Giovanni Cassini was an Italian mathematician, and astronomer. He discovered the gap between Saturn's rings caused by gravitational pull from one of Saturn's moons. This is also called the Cassini Division. He also discovered four of Saturn's moons. The Cassini Space Probe was named after him. -
Sir Isaac Newton
Isaac Newton was an English astronomer and mathematician most noted for his discovery of universal gravitation. He also established the three laws of motion, and invented the reflecting telescope. -
William Herschel
William Herschel was a British astronomer who was known for studying the Great Orion Nebula and discovering the planet Uranus, in which he first thought was a comet. He also surveyed stars and built many large telescopes. -
Percival Lowell
Percival Lowell was an American mathematician, astronomer, and businessman. He is known for started to theorize that there were canals on Mars. He also started the search for Planet X, which led to the discovery of Pluto 14 years after his death. He founded the Lowell Observatory in Arizona. -
Karl Jansky
Karl Jansky was an American radio engineer and physicist. He considered to be one of the founding figures of radio astronomy. He first discovered radio waves being emitted from the Milky Way Galaxy. The Jansky Crater on the moon is named after him, and so is the radio unit used by radio astronomers to determine the strength of astronomical radio waves -
Edwin Hubble
Edwin Hubble was an American astronomer known for his many contributions to astronomy, such as the discovery of many more galaxies beyond ours, and our constantly expanding galaxy. The Hubble Telescope is named after him. -
Albert Einstein
Albert Einstein was a German theoretical physicist known for creating the theory of relativity. He is also known for the famous E=MC(2) equation, a mass-energy equivalence formula. -
Sputnik
Sputnik was a Russian satellite launched by the Soviet Union on October 4th, 1957. It was the first artificial Earth satellite, which orbited for three weeks before the batteries had died. It triggered and launched the famous space race between the United States and the Soviet Union. -
Yuri Gagarin
Yuri Gagarin was a pilot and cosmonaut from the Soviet Union. He was the first human in space, when he completed one orbit of the Earth on 12 April 1961. He was awarded many titles, most notably the nation's highest honor, Hero of the Soviet Union. -
John Glenn
John Glenn was an American astronaut, engineer, politician, businessman, and United States Marine Corps pilot. He was the first American to orbit Earth in which he circled three times in 1962. Later, he served as a democratic senator for Ohio. -
The Apollo Program
The Apollo Space Program was a human spaceflight program formed by NASA, and the third overall major American space program conducted. Most notable and famous missions were Apollo 11 (landed men on the moon for the first time), and Apollo 13 (burst oxygen tank; movie based on the event was made). -
Ejnar Hertzsprung
Ejnar Hertzsprung was a Danish astronomer and chemist who established the classification of stars based on their color. Working with Henry Norris Russell, he created the Hertzsprung-Russell Diagram, where the absolute magnitude of of stars are plotted against their spectral types. -
Neil Armstrong
Neil Armstrong was an American astronaut, and the first person the step foot on the Moon in 1969. He and Buzz Aldrin were the first to walk on the Moon while pilot Michael Collins orbited the moon until Aldrin and Armstrong had collected samples and completed their surveys. This mission is referred to as Apollo 11. -
First Space Shuttle Flight
The first space shuttle flight, STS-1, was part of the fourth human spaceflight program conducted by NASA, the Space Shuttle Program. The shuttle, Columbia, was launched on April 12, 1981, and lasted 54.5 hours after launch, orbiting the Earth 36 times. -
Mars Pathfinder Expedition
The Mars Pathfinder was a mars rover mission launched on December 4th, 1996. It served as a demonstration of the first rover landed on Mars, and took observations of climate, weather, geologic composition, and atmosphere. -
Cassini-Huygens Orbiter
The Cassini-Huygens orbiter was a probe that was sent to study Saturn's system, including its rings and satellites. It was the first probe to enter Saturn's orbit, and the fourth probe to visit the planet. The probe took measurements and pictures of Saturn and some of Jupiter. The probe's mission lasted around 19 years, and 335 days. -
China Lands on Far Side of Moon
On January 3rd, 2019, China had successfully landed their Chang'e-4 probe on the dark side of the Moon, the rugged side of the natural satellite that always faces away from Earth. It has taken photos, collected geographic samples, and plans to attempt to plant the first flower on the Moon.
