#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<au>al-Sufi<tit>Book of Fixed Stars<d>963<c>Persia
#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
// 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<au>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 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
#e <t>obs<au>Galileo<n>Jupiter's four large moons<d>1610 Jan 7
#e <t>pub<t>astro<au>Galileo<tit>Dioptrice<d>1611
#e <t>astro<d>1635<n>Galileo forced to recant<au>Galileo<info>An inquisition forces Galileo to renounce the heliocentric theory.
#p <o>astronomer<nat>German<n>Johannes Kepler<b>1571 Dec 27<d>1630
#e <t>astro theory<d>1595<au>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>astro theory<au>Kepler<n>laws of planetary motion<d>1609
#e <t>meeting<t>astro<d>1600 Feb 4<n>Kepler and Brahe meet<c>Prague
#e <t>constr<t>astro<d>1917<n>Mount Wilson telescope<c>Mount Wilson<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>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.
// 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>Mount Wilson<au>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<au>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<au>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.
