Home > Timeline of solar system astronomy

• 2137 BC , October 22 - 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 MoonFor other moons in the solar system see natural satellite. For other uses see Moon (disambiguation). The Moon is the only natural satellite of Earth. It has no formal name other than "The Moon" although it is occasionally called Luna ( Latin for moon to d to estimate that the Moon's radius is one-third that of the Earth
• 200 BCCenturies: 3rd century BC 2nd century BC 1st century BC Decades: 250s BC 240s BC 230s BC 220s BC 210s BC 200s BC 190s BC 180s BC 170s BC 160s BC 150s BC Years: 205 BC 204 BC 203 BC 202 BC 201 BC 200 BC 199 BC 198 BC 197 BC 196 BC 195 BC Events Rome declar - EratosthenesEratosthenes ( 276 BC 194 BC) was a Greek mathematician, geographer and astronomer with (probably) Chaldean origins. He was born in Cyrene (now Shahhat, Libya) and he died in Ptolemaic Alexandria. He is noted for devising a system of latitude and longitud uses shadows to determine that the radius of the Earth is roughly 6,400 km
• 150 BCCenturies: 3rd century BC 2nd century BC 1st century BC Decades: 200s BC 190s BC 180s BC 170s BC 160s BC 150s BC 140s BC 130s BC 120s BC 110s BC 100s BC Years: 155 BC 154 BC 153 BC 152 BC 151 BC 150 BC 149 BC 148 BC 147 BC 146 BC 145 BC Events Alexander B - HipparchusFor the Athenian tyrant, see Hipparchus (son of Pisistratus). Hipparchus ( Greek pi;παρχο&sigmaf (circa 190 BC circa 120 BC) was a Greek astronomer, astrologer, geographer, and mathematician. The ESA's Hipparcos Space Astrometry M uses parallaxParallax is the change of angular position of two stationary points relative to each other as seen by an observer, due to the motion of said observer. Or more simply put, it is the apparent shift of an object against a background due to a change in observ to determine that the distance to the Moon is roughly 380,000 km
• 134 BCCenturies: 3rd century BC 2nd century BC 1st century BC Decades: 180s BC 170s BC 160s BC 150s BC 140s BC 130s BC 120s BC 110s BC 100s BC 90s BC 80s BC Years: 139 BC 138 BC 137 BC 136 BC 135 BC 134 BC 133 BC 132 BC 131 BC 130 BC 129 BC Events John Hyrcanus - Hipparchus discovers the precessionPrecession (also called gyroscopic precession is the phenomenon by which the axis of a spinning object (e. a part of a gyroscope) "wobbles" when a torque is applied to it. The phenomenon is commonly seen in a spinning toy top, but all rotating objects can 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 Domenico Cassini discovers Jupiter's great red spot
• 1656 - Christiaan Huygens identifies Saturn's rings as rings and discovers Titan and the Orion Nebula
• 1665 - Cassini determines the rotational speeds of Jupiter, Mars, and Venus
• 1672 - Cassini discovers Rhea
• 1672 - Jean Richer and Cassini measure the astronomical unit to be about 138,370,000 km
• 1675 - Ole Rømer 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 Wilhelm 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 Mécanique 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 - Édouard 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
• 1959 - Luna 3 sends a picture of the far side of the Moon
• 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