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322 BCE
Aristotle
Aristotle was an Ancient Greek Philosopher. He was the founder of a school Lyceum in Athens, Greece. -
168
Ptolemy
Latin in full Claudius Ptolemaeus. Egyptian, astronomer, mathematician, and geographer of Greek descent. -
1543
Copernicus
Polish astronomer who proposed that the planets have the sun as the fixed point to which their motions are to be referred. Wrote a manuscript called the Commentariolus. -
Tycho Brahe
Developing astronomical instruments. Fixing positions of stars paved the way for future discoveries. -
Hans Lippershey
Lippershey applied to States General of Netherlands for 30-year patent for instrument. States General granted Lippershey 900 florins for instrument. -
Johannes Kepler
Johannes Kepler was a German astronomer who discovered three major laws of planetary motion. Planets move in orbits, time, periodic times. -
Galileo
Italian natural philosopher, astronomer, and mathematician. Made fundamental contributions to sciences of motion, astronomy, and strength of materials. -
Giovanni Cassini
Italian-born French astronomer. Early studies were principally observations of the Sun. -
Sir Isaac Newton
English physicist and mathematician. Original discoverer of the infinitesimal calculus. -
William Herschel
Founder of sidereal astronomy. Discovered the planet Uranus -
Percival Lowell
Discovered the planet Pluto. Was counselor and foreign secretary to Korean Special Mission to US. -
Karl Jansky
American engineer whose discovery of radio waves from an extraterrestrial source inaugurated the development of radio astronomy. Joined the Bell Telephone Laboratories in New Jersey. -
Edwin Hubble
American astronomer who played a crucial role in establishing the field of extragalactic astronomy. Regarded as the leading observational cosmologist of the 20th century. -
Albert Einstein
Developed the special and general theories of relativity and won the Nobel Prize for Physics in 1921. Considered the most influential physicist of the 20th century. -
Sputnik
The first artificial Earth satellite. Soviet Union launched it into an elliptical low Earth orbit on 4 October 1957, orbiting for three weeks before batteries died, then silently for two more months before falling back into the atmosphere. -
John Glenn
The first U.S. astronaut to orbit Earth. He completed three orbits in 1962. He joined the U.S. Naval Reserve in 1942. -
Ejnar Hertzsprung
Had no formal education in astronomy. Appointed assistant director of the university observatory at Leiden, Neth., in 1919 and became director in 1935. -
Yuri Gagarin
He was a Soviet pilot and cosmonaut. He became the first human to journey into outer space when his Vostok spacecraft completed one orbit of the Earth on 12 April 1961.
