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569 BCE
Pythagoras
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Period: 569 BCE to 475 BCE
Pythagoras
A mathematician whose theorem is taught in high-school mathematics to this day.
The Pythagorean astronomical system was the first to propose that the planets and stars move in circles, although he theorized that our Earth and Sun orbited an as-yet-unseen “Central Fire”. -
190 BCE
Hipparchus
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Period: 190 BCE to 120 BCE
Hipparchus
Hipparchus was the founder of trigonometry and is viewed as a founding father of astronomy having put together the first known star catalog to organize 850 astronomical objects (which was later used extensively by Ptolemy).
He created a system for predicting solar eclipses and studied them to help determine the distance from the Earth to the Moon. -
100
Claudius Ptolemy
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Period: 100 to 170
Claudius Ptolemy
An astronomer who used Hipparchus’ extensive observations to develop a model that predicted the movements of the Sun, Moon, planets, and stars. His model, called the Ptolemaic system, visualized an Earth-centered universe and assumed that all astronomical objects move at constant speeds in circular orbits. The Ptolemaic model is one of the longest upheld scientific theories in history and it was the cornerstone of astronomy for 1,500 years. -
1564
Galileo Galilei
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Period: 1564 to
Galileo Galilei
Known as the “Father of Observational Astronomy”, he was among the first to use a telescope to observe the sky after hearing about its invention in the Netherlands. He constructed a 20x refractor telescope himself in 1609 and he was able to make a number of major discoveries which changed the face of astronomy.
He discovered mountains and craters on the moon, the phases of Venus, and the four largest satellites of Jupiter the first observation of satellites orbiting another planet. -
Johann Elert Bode
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Period: to
Johann Elert Bode
Published what is now known as Bode’s Law, which predicted the distances of the planets from the Sun. Using his law, he predicted an undiscovered planet between Mars and Jupiter, where the asteroid belt was later found. -
Heinrich Wilhelm Matthias Olbers
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Period: to
Heinrich Wilhelm Matthias Olbers
Olbers invented the first successful method for calculating cometary orbits. He discovered several comets, including one now called Olber’s comet and also discovered the asteroids Pallas and Vesta. He also posed Olber’s Paradox: “Why is the night sky dark?”. -
Friedrich Georg Wilhelm von Struve
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Period: to
Friedrich Georg Wilhelm von Struve
Struve is best known for his observations of double stars (a pair of stars that appear close to each other when viewed through a telescope) and published a catalog of 3000 of these. He was also first to measure the distance to the star Vega. -
Johann Gottfried Galle
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Period: to
Johann Gottfried Galle
Galle was the first astronomer to observe Neptune – after being sent calculations by Urbain Le Verrier who had predicted its existing using mathematics.
Discovered a dark ring of Saturn and three previously undiscovered comets. -
Max Wolf
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Period: to
Max Wolf
Pioneering astrophotographer who discovered hundreds of asteroids and four supernovae. He helped uncover that dark nebulae were huge clouds of fine opaque dust using photographic techniques. -
Karl Schwarzschild
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Period: to
Karl Schwarzschild
Provided the first exact solution to Einstein’s equations of general relativity, giving an understanding of the geometry of space near a point mass.
The first to study the theory of black holes.
