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240 BCE
Eratosthenes accurately calculated the Earth's circumference by measuring the angle of the Sun's rays at two different locations.
Importance - His work showed that the Earth is a sphere and showed the way for more developments in geography, cartography, and the understanding of the Earth's size and shape.
Born: 276 BC, Cyrene, Libya, Shahat, Libya
Died: 194 BC, Alexandria, Egypt -
200 BCE
Claudius Ptolemy developed the geocentric model of the universe
Importance - It was influential in organizing and predicting the motions of celestial objects and it also contributed to the development of astronomy and astrology in the ancient world.
Born: 100 CE, Alexandria, Egypt
Died: 170 CE, Alexandria, Egypt -
1543
Nicolaus Copernicus proposed the heliocentric model of the solar system, suggesting that the Sun is at the center and the planets orbit around it.
Importance - His model challenged the geocentric model and laid the foundation for modern astronomy. It changed our understanding of the universe and showed the way for future scientific advancements.
Born: February 19, 1473, Toruń, Poland
Died: May 24, 1543, Frombork, Poland -
Tycho Brahe made accurate and extensive observations of celestial bodies
Importance: Brahe's observations of Mars helped Johannes Kepler create his laws of planetary motion. His data on Mars was crucial in Kepler's discovery that planetary orbits are elliptical rather than circular.
Born: December 14, 1546, Knutstorp Manor, Sweden
Died: October 24, 1601, Prague, Czechia -
Johannes Kepler formulated his three laws of planetary motion
Importance - They provided a mathematical foundation for understanding the solar system and were crucial in the development of Isaac Newton's theory of gravity.
Born: December 27, 1571, Weil der Stadt, Germany
Died: November 15, 1630, Regensburg, Germany -
Sir Isaac Newton formulated the law of universal gravitation
Newton's law of universal gravitation changed our understanding of celestial mechanics. Newton's work showed how classical mechanics function and influenced scientific thought for centuries.
Born: January 4, 1643, Woolsthorpe Manor House, United Kingdom
Died: March 31, 1727, Kensington, London, United Kingdom -
Albert Einsteins prediction and explanation of gravitational lensing.
Importance - This has been observed and provides important evidence for the existence of dark matter and the structure of the universe.
Born: March 14, 1879, Ulm, Germany
Died: April 18, 1955, Princeton, NJ