A brief history of astronomyPresentation Transcript
Astronomy 3000 BC - 2008 AD
A Brief History in Astronomy…
3100 BC Stonehenge (Wiltshire, UK)
3000 BC Pyramids (Egypt)
1000 BC Temple of the Sun (Tiahuanaco, Bolivia)
1000 AD The Caracol (Chichen Itza, Yucatan Peninsula)
1300 AD Casa Grande (Arizona, USA)
1200-1700 AD Bighorn Medicine Wheel (Wyoming, USA)
585 BC Thales of Miletus predicted eclipse 300 BC Aristotle found Earth is not flat Position of pole star in Greece different when viewed in Egypt. 280 BC Aristarchus estimated relative distances of Sun and Moon 270 BC Eratosthenes measured circumference of Earth: 39984 km (40000 km actual value) 7.5º Well at Syene Pillar at Alexandria Sunlight Shadow Distance = 5000 stadia
300 BC Aristarchus suggested all planets orbit the Sun 150 BC Hipparchus compiled a star catalogue; discovered precession of the Earth (change in position of the pole) 120 AD Ptolemy explained motion of planets as epicycles Sun, Moon and planets Mercury, Venus, Mars, Jupiter and Saturn move around in the sky. Introduced epicycles to explain retrograde motion of some planets. Earth Order: Earth-Moon-Mercury-Venus-Sun-Mars-Jupiter-Saturn-sphere of fixed stars Earth Planet Epicycle Deferent
700 AD Ptolemy’s book translated into Arabic 830 AD Caliph Al-Mamun builds an observatory and library in Baghdad making it the astronomical centre of the world 1433 Last great Arab astronomer Ulugh Beigh sets up an observatory in Samarqand, Uzbekhistan Very accurate measurements made with the naked eye.
1500 Poland, Nicolaus Copernicus (Mikolaj Kopernik) - heliocentric model Found Ptolemaic system too messy and put Sun at centre instead of Earth. Didn’t publish his work till he was dying in 1543 for fear of imprisonment by the Church. Still thought orbits should be circular and brought back epicycles. 1570 Denmark, Tycho Brahe - parallax, stellar distances Produced revised star catalogue with precise positions of planets as they moved. He did not accept the Copernican system and preferred a system whereby the planets orbited the Sun, which orbited the Earth. 1600s Germany, Johannes Kepler - 3 laws to describe planetary orbits Movement of Mars could not be explained by Ptolemaic or Copernican system; he found its orbit was elliptical. Planet Sun
1600s Holland, telescopes invented 1610 Italy, Galileo Galilei proved heliocentric model was correct Using a telescope he see mountains and craters on the Moon and realised the band of light across the star was a vast collection of stars (the Milky Way). He found 4 satellites around Jupiter and that Venus shows phases like the Moon, thus disproving once and for all the Ptolemaic theory. He was labelled a heretic by the Church in Rome and spent the rest of his life under house arrest at his villa. Galileo’s observatory in Padua
1700s England, Isaac Newton derived 3 physical laws In 1687 he published his famous work ‘Philosophiae Naturalis Principa Mathematica’ containing the laws of universal gravitation. He built the first reflecting telescope; he showed that light was made up of many colours using a prism and he also independently invented calculus, an essential branch of mathematics.
1700s England, John Flamsteed and Christopher Wren build the Royal Greenwich Observatory for the primary purpose of producing an extensive star catalogue for use by British sea navigators. Flamsteed was the first Astronomer Royal. Edmond Halley was the second Astronomer Royal and became famous after predicting the return of a comet. He also discovered several bright stars had shifted in position since the time of Ptolemy. Image courtesy of Spike Gowers
Denmark, Ole Romer measures the velocity of light France, Giovanni Cassini at the Paris observatory discovers a gap in Saturn’s rings and several of the satellites England, William Herschel discovers Uranus He also discovered and catalogued thousands of double stars, star clusters, nebulae and galaxies, making him the ‘father of stellar astronomy’. He measured the shape of the Milky Way, which looked like 2 fried eggs back to back. He placed the Sun at the centre, when in actual fact it is 30 000 lyrs from there. France, Charles Messier creates the Messier catalogue of objects His main interest was in comets and he catalogued other objects e.g. Andromeda - M31 to distinguish them from comets. England, John Goodricke discovers some stars with variable light are actually eclipsing binary systems.
1814 Germany, Josef Von Fraunhofer discovers dark lines in the Sun’s spectrum These gaps are caused by the absorption of specific wavelengths of light by atoms in the Sun. 1845 Ireland, Earl of Rosse makes the largest telescope yet A 183 cm mirror helps him see the spiral nature of some objects; 80 years later these are found to be independent galaxies. 1846 England & France, two mathematicians predict the presence of Neptune Some unknown force was pulling Uranus out of position and it was found to be Neptune moving in a larger orbit.