Astronomy Timeline

c1265				Roger Bacon advocates experimentation. Bacon was among the first to recommend experimentation as the best way to acquire scientific knowledge. P 53.
1300				Dante describes medieval picture of universe in "Divine Comedy". Dante's picture of the universe has the Earth at its center, surrounded by the spheres of the Moon, Sun, planets, the fixed stars, a crystalline sphere and, finally, paradise. P 53. F 4.1.
c1330				Jean Buridan develops impetus theory of motion. Buridan's theory of motion was remarkable in that it contradicted the established ideas of Aristotle. P 53.
c1350				Oresme describes "Galilean" relativity. Oresme pointed out that we perceive only relative motion and that the daily motion of the stars could be explained either by the rotation of the Earth or the rotation of the celestial sphere. P 53.
c1420				Ulugh Beg builds observatory at Samarkand. Beg also compiled a star catalog based on his own observations. P 52.
c1465				Regiomontanus uses printing to produce astronomy books and tables. Regimontanus used the recently invented art of printing to produce books, almanacs, and tables of predictions of the positions of the Sun, Moon, and planets. P 53.
1504				Columbus uses lunar eclipse prediction to influence Arawaks. From his almanac, Columbus knew that a lunar eclipse would occur on February 29. He impressed the Arawaks with his accurate prediction that the Moon would rise "inflamed with wrath". P 175.
1543				Copernicus publishes "De Revolutionibus". De Revolutionibus, Copernicus's description of his heliocentric model of the solar system, was published two months before his death. P 53-59.
1572				Tycho observes supernova. Tycho's book about his observations of the supernova established his reputation as an astronomer. P 59.
c1580				Tycho carries out best pre-telescopic observations ever. Tycho's observations, made using specially built instruments, were the most accurate ever made with the naked eye. Tycho also invented his own geocentric model of the solar system. Pp 59-60. F 4.10, 4.11, 4.12.
c1600				Galileo begins experiments with falling and rolling bodies. Galileo's experiments led him to conclude that once something is set in motion it will remain in motion unless something stops it. This contradicted earlier ideas that said only rest was a natural state. Pp 72-73. F 5.1, 5.2.
1600				William Gilbert proposes Earth has dipole magnetic field. Gilbert proposed that the Earth acts like a big magnet whose field aligns the small magnet used as a compass needle. P 151.
1600				Giordano Bruno burned at stake. Bruno was tried before the Inquisition and burned for heresy. Among his heresies was the idea that there were Earth-like, inhabited planets orbiting the infinitely many stars. P 625.
1604				Kepler observes supernova. The telescope was invented a few years after Kepler carried out extensive naked-eye observations of the supernova of 1604. Since the invention of the telescope no supernovas have been observed in the Milky Way. P 459.
1609				Galileo uses telescope for astronomical observations. Galileo didn't invent the telescope but he was among the first to use a telescope to examine the heavens. He carried out important observations of the Sun, Moon, Planets, and Stars. P 64. F 4.17.
1609				Galileo observes Moon. Galileo found that the Moon had mountains, valleys, and plains like the Earth. He called the dark regions of the Moon maria, the Latin word for seas. P 64. F 4.16.
c1610				Kepler discovers laws of planetary motion. Working with Tycho's observations, Kepler discovers the shapes of planetary orbits, how the speed of a planet varies as it orbits the Sun, and the relationship between orbital distance and orbital period. Pp 61-63. F 4.13, 4.14, 4.15.
1610				Galileo observes phases of Venus. Galileo's found that Venus shows all the phases from new to full. This observation was incompatible with the Ptolemaic model of the solar system. P 64. F 4.18.
1610				Galileo discovers four largest satellites of Jupiter. Galileo found that Jupiter is orbited by four large satellites, now called, collectively, the Galilean satellites. This proved that at least some celestial bodies didn't orbit the Earth. P 64. F 4.18.
1620				Francis Bacon suggests that Earth's continents move about. Bacon noticed that the eastern and western shores of the Atlantic were parallel and could be fitted together. P 154. F 8.17.
c1630				Descartes develops concept of inertial motion. Descartes believed that all motion resulted from collision with particles called "corpuscles". In the absence of such collisions, a body remains at rest. An object in motion continues to move in the same direction at the same speed. P 73.
1632				Galileo publishes "The Dialogue". The Dialogue, although superficially a balanced debate about the merits of the geocentric and heliocentric models of the solar system, was in fact a powerful argument for the ideas of Copernicus. Galileo was brought before the Inquisition and spent the last nine years of his life under house arrest. Pp 66-67.
1640-1700				Maunder minimum. During the Maunder minimum almost no spots were seen on the Sun. This was also a time of cold climate in Western Europe and North America. P 404. F 17.33.
1654				Bishop Ussher uses Bible to calculate age of Earth. From the chronology of Biblical events, Ussher concluded that the Earth was created in 4004 BC. P 148.
1659				Christiaan Huygens realizes that the "appendages" of Saturn are rings. Huygens watched the appendages disappear in 1665 and reappear several years later. He realized that the appendages were really flat rings that disappeared when viewed edge on. P 269. F 12.25.