Famous Astronomers

Timeline created by A$VP Josh
  • Feb 19, 1473

    Nicolaus Copernicus

    Nicolaus Copernicus
    Proposed Earth orbited the Sun via De Revolutionibus Orbium Coelestium contradicting the long held Ptolomic belief that the Sun orbited the Earth thereby laying the groundwork for Galileo and Kepler.
  • Dec 14, 1546

    Tycho Brahe

    Tycho Brahe
    Chronicled supernova of 1572 and discovered it had no diurnal parallax proving it lay beyond the Moon, plotted the motion of the comet of 1577, accurately plotted motions of planets used by Kepler after his death.
  • Feb 15, 1564

    Galileo Galilei

    Galileo Galilei
    Resolved the stars in the Milky Way, discovered sunspots and measured the Sun’s rotation, observed Venus phases, discovered four moons of Jupiter, observed lunar features and measured lunar wobble, supported the Copernican system of planetary movement via his observations.
  • Dec 27, 1571

    Kepler Johannes

    Kepler Johannes
    Using Brahe’s precise data derived his three laws of planetary elliptical motion, provided explanation of optical image formation through small apertures, the first enunciation of the inverse square law for intensity of illumination.
  • Giovanni Domenico Cassini

    Giovanni Domenico Cassini
    Measured Mars and Jupiter rotation periods, first scientific records of zodiacal light, discovered the Cassini division, and investigated atmospheric refraction.
  • Edmond Halley

    Edmond Halley
    Astronomer Royal, discovered Omega Centauri, paid for publishing Newton’s Principia, using Newton’ gravitational law predicted the comet of 1682 would return in 76 years, invented the idea of using transits of Mercury and Venus to determine distance to the Sun.
  • Herschel William

    Herschel William
    The discoverer of Uranus and several satellites of Saturn and Uranus, discovered that some double stars orbit each other, discovered infrared radiation, attempted to map the Milky Way’s shape, known for building state-of-the-art telescopes.
  • Pierre-Simon Laplace

    Pierre-Simon Laplace
    Postulated the solar system evolved from a large flattened cloud of gas, published differential equations describing planetary orbits and tides, determined the masses of Jupiter, Saturn and Uranus, applied probability theory to errors in observations.
  • OLBERS Heinrich

    OLBERS Heinrich
    Discovered several comets, searched for missing planet between Mars and Jupiter forecasted by Bode’s Law and discovered Pallas and Vesta suggesting these were fragments of the missing planet, formulated Olber’s Paradox.
  • Friedrich Bessel

    Friedrich Bessel
    Father of modern astrometry, published first accurate stellar parallax, discovered orbital deflections of Sirius and Procyon from unseen white dwarfs.
  • William Huggins

    William Huggins
    nvented the stellar spectroscope, comparing laboratory and stellar spectra demonstrated that the Orion nebula's pure emission spectra indicated its gaseous nature while Andromeda galaxy had continuous spectra, imaged solar prominences in H Alpha light.
  • George Ellery Hale

    George Ellery Hale
    The first astrophysicist, invented the spectroheliograph allowing photography of solar prominences in daylight, discovered magnetic fields in sunspots, planned and completed the 200-inch Mt. Palomar telescope.
  • Ejnar Hertzsprung

    Ejnar Hertzsprung
    Studied stellar proper motions and motions of binary stars, using photography studied stellar brightness, compared stellar color ratios, plotted color-magnitude diagram for the Hyades cluster, which evolved to the Hertzsprung-Russell diagram.
  • Edwin Hubble

    Edwin Hubble
    Discovered the Hubble classification of galaxies, using Cepheid variables in M31 and M33 calculated their distances, showed that galaxy distribution was cosmologically uniform, showed galaxies were moving away from us at speeds proportional to their distance
  • Baade Wilhelm

    Baade Wilhelm
    Proposed supernova could produce cosmic rays and neutron stars, first resolved stars in Andromeda galaxy, defined Population I and II stars and two kinds of Cepheid variables.