- 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 Rżmer 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
Timeline of Solar System Astronomy
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