Astronomy Timeline

  • 200


    His extant writings span a wide range of disciplines, from logic, metaphysics and philosophy of mind, through ethics, political theory, aesthetics and rhetoric, and into such primarily non-philosophical fields as empirical biology, where he excelled at detailed plant and animal observation and taxonomy.
  • 200

    aristarchus of samos

    aristarchus of samos
    The first of the Greek philosphers and mathematicians to unravel the celestial plan and announce the discovery was Aristarchus of the isle of Samos. Others before him assumed that the Earth is a sphere and that it moves, but he was the first to formulate plainly the heliocentric theory, the scheme which has the Sun in the center.
  • 200


    One of the important works of Eratosthenes was Platonicus which dealt with the mathematics which underlie Plato's philosophy. This work was heavily used by Theon of Smyrna when he wrote Expositio rerum mathematicarum and, although Platonicus is now lost, Theon of Smyrna tells us that Eratosthenes' work studied the basic definitions of geometry and arithmetic, as well as covering such topics as music
  • 200


    Pythagoras made influential contributions to philosophy and religious teaching in the late 6th century BC. He is often revered as a great mathematician, mystic and scientist, and he is best known for the Pythagorean theorem which bears his name.
  • 200


    Hipparchus measured the distance from the Earth to the Moon during a solar eclipse Hipparchus also measured the precession of the Earth's rotation axis. Today we know that the precession period is about 26,000 years
  • Feb 2, 1473


    Copernicus is said to be the founder of modern astronomy
    In 1530, Copernicus completed and gave to the world his great work De Revolutionibus, which asserted that the earth rotated on its axis once daily and traveled around the sun once yearly
  • Dec 14, 1546

    Tycho Brahe

    Tycho Brahe
    In his De nova stella (Of new stars) of 1573, he refuted the theory of the celestial spheres by showing the celestial heavens were not in an immutable or unchanging state of perfection as previously assumed by Aristotle and Ptolemy. His precise measurements indicated that "new stars" (now known as novae or supernovae), in particular that of 1572, lacked the parallax expected in sub-lunar phenomenon, and were therefore not "atmospheric" tail-less comets as previously believed, but occurred above
  • Feb 15, 1564

    Galileo Galilei

    Galileo Galilei
    Galileo pioneered "experimental scientific method" and was the first to use a refracting telescope to make important astronomical discoveries.
  • Dec 27, 1571

    Johannes Kepler

    Johannes Kepler
    He is best known for his eponymous laws of planetary motion, codified by later astronomers, based on his works Astronomia nova, Harmonices Mundi, and Epitome of Copernican Astronomy. During his career, Kepler was a mathematics teacher at a seminary school in Graz,
  • Isaac Newton

    Isaac Newton
    gave future scientists the tools to discover how to enter space. He discovered gravitational force and established the three Universal Laws of Motion. he established classic mechanics the beginning of modern Physics. was the first to propose a set of laws that described the motion of all things in the universe.
  • Annie Jump Cannon

    Annie Jump Cannon
    Cannon also published catalogs of variable stars (including 300 she discovered). Her career spanned more than forty years, during which women in science won grudging acceptance. She received many "firsts" (first recipient of an honorary doctorate from Oxford, first woman elected an officer of the American Astronomical Society, etc.). At Harvard she was named Curator of Astronomical Photographs, but it was only in 1938, two years before her retirement, that she obtained a regular Harvard appointm
  • George Hale

    George Hale
    George Ellery Hale was the founding father of the Mt. Wilson Observatory. He is shown here in his office in the "monastery" on the mountain, in a picture that dates from about 1905. Despite having no earned degree beyond his baccalaureate in physics from the Massachusetts Institute of Technology in 1890, Hale became one of the leading astronomers of his day. By the time Hale established the Mt. Wilson Observatory in 1904, he had already invented the spectroheliograph,
  • Henrietta Swan Leavitt

    Henrietta Swan Leavitt
    During her career, Leavitt discovered more than 2,400 variable stars, about half of the known total in her day. Leavitt's work with variable stars led to her most important contribution to the field: the cepheid variable period-luminosity relationship. Leavitt discovered a direct correlation between the time it took a star to go from bright to dim to how bright it actually was. Knowing this relationship helped other astronomers, such as Edwin Hubble, to make their own groundbreaking discoverie
  • Albert Einsein

    Albert Einsein
    Einstein's researches are, of course, well chronicled and his more important works include Special Theory of Relativity (1905), Relativity (English translations, 1920 and 1950), General Theory of Relativity (1916), Investigations on Theory of Brownian Movement (1926), and The Evolution of Physics (1938). Among his non-scientific works, About Zionism (1930), Why War? (1933), My Philosophy (1934), and Out of My Later Years (1950) are perhaps the most important.
  • Edwin Hubble

    Edwin Hubble
    Hubble devised a classification system for the various galaxies he observed, sorting them by content, distance, shape, and brightness; it was then he noticed redshifts in the emission of light from the galaxies, seeing saw that they were moving away from each other at a rate constant to the distance between them. From these observation, he was able to formulate Hubble's Law in 1929, helping astronomers determine the age of the universe, and proving that the universe was expanding.
  • Gerald Kuiper

    Gerald Kuiper
    He is considered the father of modern planetary science for his brilliant study of our solar system Kuiper developed new techniques of looking at the sky, and discovered a moon of Neptune and Uranus. He also found that Titan had an atmosphere similar to our own. Kuiper suggested that there was a belt of comet-like debris at the edge of our solar system, a theory that was proven true 20 years after his death.
  • Bengt Georg Daniel Stromgren

    Bengt Georg Daniel Stromgren
    Some gaseous nebulae that can be observed within our Galaxy are luminous. Strömgren proposed that this light was caused by hot stars within obscuring layers of gas in the nebulae. He suggested that these stars ionize hydrogen gas and that the dimensions of the ionized zone (the Strömgren sphere) depend on both the density of the surrounding gas and the temperature of the star. His calculations of the sizes of these zones have been confirmed by observations.
  • Subrahanyan Chandrasekhar

    Subrahanyan Chandrasekhar
    Chandrasekhar was noted for his work in the field of stellar evolution, and in the early 1930s he was the first to theorize that a collapsing massive star would become an object so dense that not even light could escape it. went on to form the foundation of the theory of black holes, and eventually earned him a shared Nobel Prize in physics for 1983.
  • Grote Reber

    Grote Reber
    Reber built a 9-m dish antenna in his backyard and equipped it with three different detectors before finding signals at a wavelength of 1.9 m. His 1940 and 1944 publications of articles titled “Cosmic Static” in the Astrophysical Journal marked the beginning of intentional radio astronomy. He was the first to express received radio signals in terms of flux density and brightness, the first to find evidence that galactic radiation is nonthermal, and the first to produce radio maps of the sky.
  • James Van Allen

    James Van Allen
    1940: As a staff physicist for the Department of Terrestrial Magnetism of the Carnegie Institution in Washington, D.C., Van Allen worked on developing photoelectric and radio Proximity fuses for bombs, rockets, and gun-fired projectiles. It was here that Van Allen acquired his interest in cosmic rays.
    1942: Van Allen joined the Applied Physics Laboratory (APL) of Johns Hopkins University to continue his work on proximity fuzes. Later in 1942, he entered the Navy, serving in the South Pacific Fle
  • Sir Fred Hoyle

    Sir Fred Hoyle
    noted primarily for his contribution to the theory of stellar nucleosynthesis and his often controversial stance on other cosmological and scientific matters—in particular his rejection of the "Big Bang" theory, a term originally coined by him as a jocular, perhaps disparaging, name for the theory which was the main rival to his own.
  • E. Margaret Burbidge

    E. Margaret Burbidge
    studied the spectra of galaxies, nuclear reactions at the center of stars, and conducted spectroscopic surveys of quasars.
    she developed a better explanation of how elements are formed by nuclear reactions inside stars.
  • Eugene Shoemaker

    Eugene Shoemaker
    a legendary geologist who influenced decades of research on the role of asteroids and comets in shaping the planets.
    perhaps most famous for finding the comet (Shoemaker-Levy 9) that broke up and collided with Jupiter in 1994.
  • Thomas Mutch

    Thomas Mutch
    He published two books about the geology of the Moon and of Mars. As head of the Viking surface photography team, he is quoted as commenting on the first pictures: "This is just an incredible scene. It looks safe and very interesting."