Timeline of solar system astronomy

  • 2136 BC - Chinese astronomers record a solar eclipse
  • 586 BC - Thales of Miletus predicts a solar eclipse
  • 350 BC - Aristotle argues for a spherical Earth using lunar eclipses and other observations
  • 280 BC - Aristarchus uses the size of the Earth's shadow on the Moon to estimate that the Moon's radius is one-third that of the Earth
  • 200 BC - Eratosthenes uses shadows to determine that the radius of the Earth is roughly 6,400 km
  • 150 BC - Hipparchus uses parallax to determine that the distance to the Moon is roughly 380,000 km
  • 134 BC - Hipparchus discovers the precession of the equinoxes
  • 1512 - Nicholas Copernicus first states his heliocentric theory in Commentariolus
  • 1543 - Nicholas Copernicus shows that his heliocentric theory simplifies planetary motion tables in De Revolutionibus de Orbium Coelestium
  • 1577 - Tycho Brahe uses parallax to prove that comets are distant entities and not atmospheric phenomena
  • 1609 - Johannes Kepler states his first two empirical laws of planetary motion
  • 1610 - Galileo Galilei discovers Callisto, Europa, Ganymede, and Io
  • 1610 - Galileo Galilei sees Saturn's planetary rings but does not recognize that they are rings
  • 1619 - Johannes Kepler states his third empirical law of planetary motion
  • 1655 - Giovanni Cassini discovers Jupiter's great red spot
  • 1656 - Christian Huygens identifies Saturn's rings as rings and discovers Titan and the Orion Nebula
  • 1665 - Giovanni Cassini determines the rotational speeds of Jupiter, Mars, and Venus
  • 1672 - Giovanni Cassini discovers Rhea
  • 1672 - Jean Richer and Giovanni Cassini measure the astronomical unit to be about 138,370,000 km
  • 1675 - Ole RÝmer uses the orbital mechanics of Jupiter's moons to estimate that the speed of light is about 227,000 km/s
  • 1705 - Edmund Halley publicly predicts the periodicity of Halley's Comet and computes its expected path of return in 1758
  • 1715 - Edmund Halley calculates the shadow path of a solar eclipse
  • 1716 - Edmund Halley suggests a high-precision measurement of the Sun-Earth distance by timing the transit of Venus
  • 1758 - Johann Palitzsch observes the return of Halley's comet
  • 1766 - Johann Titius finds the Titius-Bode rule for planetary distances
  • 1772 - Johann Bode publicizes the Titius-Bode rule for planetary distances
  • 1781 - William Herschel discovers Uranus during a telescopic survey of the northern sky
  • 1796 - Pierre Laplace states his nebular hypothesis for the formation of the solar system from a spinning nebula of gas and dust
  • 1801 - Giuseppe Piazzi discovers the asteroid Ceres
  • 1802 - Heinrich Olbers discovers the asteroid Pallas
  • 1821 - Alexis Bouvard detects irregularities in the orbit of Uranus
  • 1825 - Pierre Laplace completes his study of gravitation, the stability of the solar system, tides, the precession of the equinoxes, the libration of the Moon, and Saturn's rings in Mecanique Celeste
  • 1843 - John Adams predicts the existence and location of Neptune from irregularities in the orbit of Uranus
  • 1846 - Urbain Le Verrier predicts the existence and location of Neptune from irregularities in the orbit of Uranus
  • 1846 - Johann Galle discovers Neptune
  • 1846 - William Lassell discovers Triton
  • 1849 - Edouard Roche finds the limiting radius of tidal destruction and tidal creation for a body held together only by its self gravity, called the Roche limit, and uses it to explain why Saturn's rings do not condense into a satellite
  • 1856 - James Clerk Maxwell demonstrates that a solid ring around Saturn would be torn apart by gravitational forces and argues that Saturn's rings consist of a multitude of tiny satellites
  • 1866 - Giovanni Schiaparelli realizes that meteor streams occur when the Earth passes through the orbit of a comet that has left debris along its path
  • 1906 - Max Wolf discovers the Trojan asteroid Achilles
  • 1930 - Clyde Tombaugh discovers Pluto
  • 1930 - Seth Nicholson measures the surface temperature of the Moon
  • 1950 - Jan Oort suggests the presence of a cometary Oort cloud
  • 1951 - Gerard Kuiper argues for an annular reservoir of comets between 40-100 astronomical units from the Sun, the Kuiper belt
  • 1977 - James Elliot discovers the rings of Uranus during a stellar occultation experiment on the Kuiper Airborne Observatory
  • 1978 - James Christy discovers Charon
  • 1978 - Peter Goldreich and Scott Tremaine present a Boltzmann equation model of planetary-ring dynamics for indestructible spherical ring particles that do not self-gravitate and find a stability requirement relation between ring optical depth and particle normal restitution coefficient
  • 1988 - Martin Duncan, Thomas Quinn, and Scott Tremaine demonstrate that short-period comets come primarily from the Kuiper Belt and not the Oort cloud