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322 BCE
Aristotle
384-322 BC Aristotle was an Ancient Greek philosopher and scientist who is still considered one of the greatest thinkers in politics, psychology and ethics. In 335, Aristotle founded his own school, the Lyceum, in Athens, where he spent most of the rest of his life studying, teaching and writing. Aristotle's accomplishments as a philosopher (a term which in his time meant as much scientist as philosopher) were extraordinary, undoubtedly the greatest in the Western tradition. -
168
Ptolemy
100-168 AD Ptolemy, Latin in full Claudius Ptolemaeus (fl. AD 127-145, Alexandria), ancient astronomer, geographer, and mathematician who considered the Earth the center of the universe. The earliest, and perhaps most important of Ptolemy's work that has survived gives in detail the mathematical theory of the motions of the Sun, Moon, and planets. He also studied eclipses, and was the first to be able to predict when and where a solar eclipse would happen. -
1543
Copernicus
1473-1543 when virtually everyone believed Earth was the center of the universe, Polish scientist Nicolaus Copernicus proposed that the planets instead revolved around the sun. Although his model wasn't completely correct, it formed a strong foundation for future scientists to build on and improve mankind's understanding of the motion of heavenly bodies. -
Tycho Brahe
1546-1601 At the time, people believed in a geocentric model of the universe with the earth at the center. Tycho Brahe was a Danish nobleman and astronomer, and he was one of the individuals whose work helped overturn that belief in favor of a model of the universe, with the sun at the center.
Brahe showed irregularities in the Moon's orbit and discovered a new star in the Cassiopeia formation. Brahe invented many instruments such as the Tyconian Quadrant. -
Hans Lippershey
1570-1619 Hans Lippershey, also known as Johann Lippershey or Lipperhey, was a German-Dutch spectacle-maker. He is commonly associated with the invention of the telescope, because he was the first one who tried to obtain a patent for it. It is, however, unclear if he was the first one to build a telescope. -
Johannes Kepler
1571-1630 Kepler is a key figure in the 17th-century scientific revolution. He is best known for his laws of planetary motion, based on his works Astronomia nova, Harmonices Mundi, and Epitome of Copernican Astronomy. These works also provided one of the foundations for Isaac Newton's theory of universal gravitation. -
Galileo
1564-1642 Galileo Galilei was an Italian astronomer, physicist and engineer, sometimes described as a polymath. He subsequently used his newly invented telescope to discover four of the moons circling Jupiter, to study Saturn, to observe the phases of Venus, and to study sunspots on the Sun. Galileo's observations strengthened his belief in Copernicus' theory that Earth and all other planets revolve around the Sun. -
Giovanni Cassini
1625-1712 Giovanni Domenico Cassini was an Italian (naturalised French) mathematician, astronomer and engineer. ... Cassini discovered four satellites of the planet Saturn and noted the division of the rings of Saturn; the Cassini Division was named after him. -
Sir Isaac Newton
1643-1724 Sir Isaac Newton was an English mathematician, physicist, astronomer, theologian, and author who is widely recognised as one of the most influential scientists of all time, and a key figure in the scientific revolution. Besides his work on universal gravitation (gravity), Newton developed the three laws of motion which form the basic principles of modern physics. His discovery of calculus led the way to more powerful methods of solving mathematical problems. -
William Herschel
1738-1822 William Herschel was a German-born British astronomer and composer, who is widely credited as the founder of sidereal astronomy for observing the heavenly bodies. He found the planet Uranus and its two moons, and formulated a theory of stellar evolution. -
Percival Lowell
1855-1916 Percival Lawrence Lowell was an American businessman, author, mathematician, and astronomer who fueled speculation that there were canals on Mars. He founded the Lowell Observatory in Flagstaff, Arizona and formed the beginning of the effort that led to the discovery of Pluto 14 years after his death. -
Karl Jansky
1905-1950 Two men who learned of Jansky's discovery in 1933 were of great influence on the later development of the new study of radio astronomy: one was Grote Reber, who singlehandedly built a radio telescope in his back yard in 1937 and did the first systematic survey of radio waves from the sky. -
Edwin Hubble
1889-1953 Edwin P. Hubble revolutionized cosmology by proving that the clouds of light astronomers saw in the night sky were actually other galaxies beyond our Milky Way. His greatest discovery was in 1929, when he identified the relationship between a galaxy's distance and the speed with which it is moving. -
Albert Einstein
1879-1955 Albert Einstein's theory of special relativity explains how space and time are linked, but it doesn't include acceleration. By including acceleration, Einstein later developed the theory of general relativity, which explains how massive objects in the cosmos distort the fabric of space-time. The theory explains how this distortion is felt as the force of gravity, as it predicts how much the mass of an object curves space-time. -
Sputnik
1957 Sputnik 1 was the first artificial Earth satellite. The Soviet Union launched it into an elliptical low Earth orbit on 4 October 1957, orbiting for three weeks before its batteries died, then silently for two more months before falling back into the atmosphere. -
Yuri Gagarin
1934-1968 April 12 was already a huge day in space history twenty years before the launch of the first shuttle mission. On that day in 1961, Russian cosmonaut Yuri Gagarin became the first human in space, making a 108-minute orbital flight in his Vostok 1 spacecraft. -
John Glenn
1921-2016 He was one of the Mercury Seven, military test pilots selected in 1959 by NASA as the nation's first astronauts. On February 20, 1962, Glenn flew the Friendship 7 mission, becoming the first American to orbit the Earth, and the fifth person and third American in space. Glenn circled Earth three times. The flight lasted a total of 4 hours, 55 minutes, and 23 seconds before the Friendship 7 spacecraft splashed down in the ocean. -
Ejnar Hertzsprung
1873-1967 Ejnar Hertzsprung was a Danish chemist and astronomer born in Copenhagen. In the period 1911–1913, together with Henry Norris Russell, he developed the Hertzsprung. -
Neil Armstrong
1930-2012
Apollo 11 was the spaceflight that landed the first two people on the Moon. Commander Neil Armstrong and Lunar Module Pilot Buzz Aldrin, both American, landed the lunar module Eagle on July 20, 1969 -
The Apollo Program
1963-1972 The Apollo program, also known as Project Apollo, was the third United States human spaceflight program carried out by the National Aeronautics and Space Administration, which succeeded in landing the first humans on the Moon from 1969 to 1972.
