#p <nat>Arab<o>astronomer<n>Mohammed al-Battani<aka>Abu Allah Mohammed Ibn Jabir al-Battani<b>850(5)<d>929<c>Baghdad<info>Al-Battani was known in Europe as Albategnius. He showed that the earth-sun distance varies throughout the year, and established a figure for the length of the year that was only 2.5 minutes too short.
#e <t>use<t>astro<n>astrolabes<c>Arabia<d>850(10)
#p <nat>Persian<o>astronomer<n>Abd al-Rahman al-Sufi<sur>al-Sufi<b>903<d>986<c>Baghdad<info>Al-Sufi was known in the West as Azophi.
#e <t>pub<t>astro<p>al-Sufi<n>Book of Fixed Stars<d>963<c>Persia<info>by @al-Sufi@@.
#p <nat>Arab<o>astronomer<n>Mohammed al-Biruni<aka>Abu ar-Rayhan Mohammed ibn Ahmad al-Biruni<b>973<d>1048
#p <nat>Persian<o>poet<o>astronomer<o>math<n>Umar al-Khayyami<aka>Umar ibn Ibrahim al-Khayyami<b>1048(2)<d>1131<c>Isfahan<info>Al-Khayyami was called Omar Khayyam in the west, where he is best known as a poet. An accomplished astronomer, he made a very precise calculation of the tropical year, and proposed a solar calendar which would have been even more accurate than the Gregorian calendar, with eight leap years of 366 days every 33 years.
#p <nat>Hebrew<o>astronomer<n>Abraham ha-Nasi<aka>Abraham bar Hiyya ha-Nasi<b>1070<d>1136<c>Barcelona
#e <t>observation<d>1054 Jul 4<n>Taurus supernova<c>China<info>Chinese astronomers were startled by the appearance of a new star in the Taurus constellation. This supernova's nebula was later @disovered@Crab Nebula@ by @Charles Messier@@.
#e <t>observation<d>1066<n>Halley's comet<c>Western Europe<info>Halley's comet was seen from Western Europe in 1066, the year of the @battle of Hastings@@.
// 14th century
#p <o>astronomer<o>ruler<n>Ulugh Beg<b>1394<d>1449<c>Samarkand<info>Beg made a calculation of the length of the tropical year which was only 25 seconds too long. He briefly ruled Samarkand, but was put to death by his own son during a coup.
// 15th century
#p <nat>Dutch<o>astronomer<o>bishop<n>Paul of Middelburg<sur>Paul of Middelburg<b>1450(1)<d>1533
#p <o>astronomer<nat>Polish<n>Nicolaus Copernicus<b>1473 Feb 19<d>1543 May 24
#e <t>pub<t>astro<p>Copernicus<n>De Revolutionibus<d>1543 May<info>In 1512, @Copernicus@@ had written a short treatise on planetary motion. It was finally published in 1530. His final work, "De revolutionibus," was inspired in part by pope @Leo X@@, who in 1514 had sent letters to European monarchs and prominent astronomers requesting advice on proposed changes to the calendar. Copernicus dedicated "De revolutionibus" to pope @Paul III@@, acknowledging that his views were controversial. Unbeknownst to him, his publisher added a preface stating that his heliocentric theory was only a model which was used to explain motions, and disclaiming the idea that the earth actually revolved around the sun. Copernicus got to see his published book on his deathbed on the day he died.
// 16th century
#p <nat>German<o>astronomer<o>priest<n>Christopher Clavius<b>1537 Mar 25<d>1612<c>Bavaria<mov>1554<c>Rome<mov>1558(2)<c>Portugal<mov>1562(2)<c>Rome<info>Clavius joined the Society of the Jesuits in Rome on April 12, 1555. He was a staunch defender of the Ptolemaic worldview. Clavius was a member of the papal commission to reform the calendar, and he defended the @1582 reform@Gregorian reform@ in six different publications.
#p <o>astronomer<nat>Danish<n>Tycho Brahe<b>1546 Dec 14<d>1601 Oct 24<c>Denmark<mov>1597<c>Prague
#p <o>astronomer<nat>Italian<o>physicist<n>Galileo Galilei<sur>Galileo<b>1564 Feb 15<d>1642
#p <o>astronomer<nat>German<n>Johannes Kepler<b>1571 Dec 27<d>1630
#e <t>astro theory<d>1595<p>Kepler<n>nested Platonic solids<info>@Kepler@@ thought the distances of the planets from the sun could be explained by nesting the six known planets' spheres between the five Platonic solids.
#e <t>meeting<t>astro<d>1600 Feb 4<n>Kepler and Brahe meet<c>Prague
#e <t>astro<d>1635<n>Galileo forced to recant<p>Galileo<info>An inquisition forces @Galileo@@ to renounce the heliocentric theory.
#e <t>obs<d>1675<p>Roemer<n>speed of light measured to within 50%<info>by @Roemer@@.
// 18th century
#p <nat>Swedish<o>astronomer<n>Anders Celsius<b>1701 Nov 27<d>1744
#p <nat>French<o>astronomer<n>Charles Messier<b>1730 Jun 26<d>1817 Apr 11(1)<c>France<info>Charles Messier compiled the well-known "Messier catalogue" of celestial objects. He was the first in France to observe Halley's comet on its return in 1759, and in subsequent years he claimed the discovery of 21 new comets. Messier compiled his catalogue of extended nebulous objects in order to distinguish them from comets.
#p <nat>English<o>astronomer<n>Sir John Herschel<sur>J. Herschel<b>1792<d>1871<fa>William Herschel
#e <t>observation<d>1758 Sep 12<n>Crab Nebula<aka>Messier 1<p>Charles Messier<info>While searching for comets, @Charles Messier@@ discovered a blurry object which he catalogued as "Messier 1," or M1. This nebula was the result of a @supernova@Taurus supernova@ some 700 years before.
#e <t>astro theory<d>1772<n>trojan orbits<p>Lagrange<info>@Lagrange@@ determined that three bodies rotating as an equilateral triangle have stable orbits. For example, if the Sun and Jupiter form two corners of the triangle, then asteroids travelling in Jupiter's orbit - but 60 degrees ahead of or behind Jupiter - should have stable orbits.
#e <t>obs<d>1781 Mar 13<n>Uranus<p>William Herschel<info>by @William Herschel@@.
// 19th century
#e <t>obs<d>1801 Jan 1<n>asteroid 1 Ceres<info>the largest and first discovered asteroid<info>Ceres was discovered by G. Piazzi.
#e <t>obs<d>1802 Jan 1<n>Ceres rediscovered<c><info>@Asteroid 1 Ceres@asteroid 1 Ceres@ was first discovered in January, 1801, and observed for several weeks by Piazzi. Shortly afterward, Ceres approached conjunction and was too close to the sun to be seen. @Gauss@@ determined an orbit for Ceres and predicted its position based on this orbit. Ceres was found again on this date within 0.5° of the position Gauss had predicted.
#e <t>obs<n>asteroid 2 Pallas<d>1802 Mar<info>the 2nd largest asteroid and 2nd asteroid discovered<info>Pallas was discovered by Heinrich Olbers.
#e <t>obs<n>asteroid 3 Juno<d>1804<info>the 3rd asteroid discovered<info>Juno was discovered by K. Harding.
#e <t>obs<n>asteroid 4 Vesta<d>1845<info>the 3rd largest asteroid<info>Vesta appears to have a basaltic crust overlying an olivine mantle.
#e <t>obs<n>asteroid 5<d>1845<info>discovered by Karl Hencke
#e <t>obs<n>Neptune<d>1846 Sep 23
#e <t>obs<d>1848<n>Triton<c>Great Britain<info>Triton, the largest satellite of Neptune, was discovered by the British astronomer William Lassell.
#e <t>obs<d>1868<n>helium on the sun<info>The element helium was first discovered by solar spectroscopy, by J. N. Lockyer in 1868.
#e <t>inv<d>1875<n>1.2-metre telescope<c>Paris
#e <t>obs<d>1877<n>Phobos and Deimos<c>U.S.<info>Asaph Hall, of the U.S. Naval Observatory, discovered Mars' two moons.
// 20th century
#e <t>observation<d>1906 Feb 12<n>first Trojan asteroid<c><info>The first @Trojan@trojan orbits@ asteroid was found on February 12, 1906.
#e <t>constr<t>astro<d>1917<n>Mount Wilson telescope<c>Los Angeles<info>Astronomer George Hale built a 100-inch reflecting telescope on Mount Wilson.
#e <t>astro theory<d>1927<n>Big Bang<c>Belgium<info>Belgian astronomer and priest Georges Lemaître proposes that the universe began with the explosion of a highly condensed mass, which he calls a "cosmic egg."
#e <t>obs<n>Pluto<d>1930 Feb 18<info>by Clyde Tombaugh
#e <t>obs<d>1965<n>cosmic background radiation<c>U.S.<info>American radio astronomers Arno Penzias and Robert Wilson accidentally discover the cosmic background radiation.
#e <t>observation<d>1987 Feb 23<n>Supernova Shelton<c>Chile<info>Astronomer Ian Shelton discovered the supernova of 1987 at the University of Toronto's Southern Observatory in Chile's Atacama Desert. The supernova occured in the Large Magellanic Cloud, and was the brightest one in 400 years.
#e <t>obs<n>Dactyl<d>1993 Aug 28<info>Dactyl, a satellite of 243 Ida, is the first known moon of an asteroid. It was imaged by the Galileo probe.
#e <t>obs<d>1994<n>Shoemaker-Levy hits Jupiter<info>Comet Shoemaker-Levy crashes into Jupiter.
#e <t>obs<d>1998 Nov 17<n>Leonid meteor shower<info>Occuring every year on November 17, the Leonid meteor shower occurs when earth crosses the orbit of comet Tempel-Tuttle. The comet has a 33.2-year orbital period, with a maximum in the meteor shower occuring after each time the comet crosses earth's orbit. Such "meteor storms" occured in 902, 1799, 1833, and 1966. In 1899 no sharp peak in Leonid activity was noted. In 1933, it is believed to have happened over an unihabited part of the earth. The 1998 storm occured over central Asia and was much smaller than expected. It returned again in 1999, but was again not a storm.
// Hubble
#p <nat>American<o>astronomer<n>Edwin Hubble<b>1889 Nov 20<d>1953 Sep 28<c>Chicago<mov>1920(2)<c>California
#e <t>obs<d>1923<n>existence of galaxies proven<c>Los Angeles<p>Hubble<info>@Hubble@@ settled a long debate by demonstrating that the Andromeda "nebula" was actually a galaxy outside our own Milky Way and that many other such galaxies exist.
#e <t>astro theory<d>1925<n>classification of galaxies<p>Hubble<info>@Hubble@@ devised a classification scheme for the structure of galaxies that is still in use today in modified form.
#e <t>astro theory<d>1929<n>Hubble's law<p>Hubble<info>@Hubble@@'s law states that the more distant a galaxy is, the faster it is receding from us. The fundamental cosmological quantity known as Hubble's constant is derived from this law.
