Timeline of Famous Astronomers

  • 384 BCE


  • Period: 384 BCE to 322 BCE

    Info - Aristotle

    Aristotle was a student of Plato. He proved that the Earth was spherical by noting that the shadow of the earth on the moon during a lunar eclipse was always circular and that the only shape that always casts a circular shadow is a sphere. He also noted that as one traveled more north or south, the positions of the stars in the sky change.
  • 190 BCE


  • Period: 190 BCE to 120 BCE

    Info - 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.
    He discovered the wobble of the Earth’s axis caused by the gravitational pull of the Sun and Moon and also created a method by which a star’s brightness is measured – a version of this magnitude system is still used today.
  • 100

    Claudius Ptolemy

    Claudius Ptolemy
  • Period: 100 to 170

    Info - Claudius Ptolemy

    Ptolemy developed a model (with the help of Hipparchus' extensive observations) that predicted the movements of the Sun, Moon, planets, and stars. He also included in his work a set of tables which made it easier to calculate the positions of the planets, the sun and the moon, the rising and setting of the stars, and the dates of lunar and solar eclipses.
  • 1473

    Nicolaus Copernicus

    Nicolaus Copernicus
  • Period: 1473 to 1543

    Info - Nicolaus Copernicus

    With Copernicus a new era of astronomy when he concluded that the Sun was the center of the universe instead of the Earth.
    In 1543 when his book (On the Revolutions of the Celestial Spheres) the theory could simply not be brushed aside any longer.
  • 1564

    Galileo Galilei

    Galileo Galilei
  • Period: 1564 to

    Info - Galileo Galilei

    Known as the “Father of Observational Astronomy”, he was among the first to use a telescope to observe the sky. Galileo constructed a 20x refractor telescope himself in 1609, discovered mountains and craters on the moon, the phases of Venus (still called the “Galilean Moons” today), and the four largest satellites of Jupiter. He was the first to lay eyes on the Rings of Saturn, observed and provided an analysis of sunspots. He advanced the theory of heliocentrism.
  • 1571

    Johannes Kepler

    Johannes Kepler
  • Period: 1571 to

    Info - Johannes Kepler

    Kepler was the first to fully explain the laws of planetary motion – which came to be known as Kepler’s Laws.
    He made a breakthrough by proposing elliptical, rather than circular, orbits of planets, was the first to explain how the moon influenced tides and also established the most exact astronomical tables then known.
  • Sir Isaac Newton

    Sir Isaac Newton
  • Period: to

    Info - Sir Isaac Newton

    He is one of the most influential scientists of all time. Newton’s book Principia formulated the laws of motion and universal gravitation that dominated scientists’ view of the physical universe for the next three centuries.
    Newton removed the last doubts about the validity of the heliocentric model of the Solar System and demonstrated that the motion of objects on Earth and of celestial bodies could be accounted for by the same principles. Newton also built the first reflecting telescope.
  • Charles Messier

    Charles Messier
  • Period: to

    Info - Charles Messier

    Messier was a comet-hunter who discovered 19 comets. His search for comets led him to create one of the most famous catalogs of 110 deep sky objects. He believed that these objects could distract other comet-chasers and so he cataloged them – being the first to do so for many galaxies, nebulae, and clusters of stars. The Messier Astronomical Catalog organized many objects in a system still used by astronomers today.
  • William Herschel

    William Herschel
  • Period: to

    Info - William Herschel

    Herschel discovered Uranus and its two brightest moons and two of Saturn’s moons. He discovered the ice caps of Mars, several asteroids, and binary stars, cataloged 2,500 deep sky objects and was the first to realize that the solar system was moving through space (and estimated the direction of the movement).
    Herschel also accidentally discovered infrared radiation when using filters during observation of sunspots.
    He built his own reflecting telescopes to observe binary systems of stars.
  • Albert Einstein

    Albert Einstein
  • Period: to

    Info - Albert Einstein

    Considered the greatest mind of the 20th century, he developed the theory of relativity.
    He later extended the principle of relativity to gravity and subsequently developed his General Theory of Relativity. According to the theory, the gravitational attraction between masses results from the warping of space and time by those masses. This is today an essential element in modern astrophysics and provides the foundation for the current understanding of black holes.