LESSON 1 – introduction to AstronomyWhat is astronomy?Astronomy is the scientific study of celestial objects (stars, planets, Galaxies and the universe as awhole.)The name derives from the Greek words Astron (“star”) and nomos (“law”)Tools of astronomyTelescope – Astronomers use telescopes to observe celestial objects. The quest to study increasinglydistant object and to see them in greater detail has led to larger and larger telescopes (e.g. Kecktelescope)Spacecraf – the planets and other objects in our own system can be studied using spacecraf that flypast, orbit or land on them.Computers – astronomers use computers to analyse their data and to produce mathematical modelsthat can be compared with observations. (e.g. The Green II supercomputer at Swinburne university)The internet – astronomical research is a global endeavour and many projects involve internationalcollaboration. To share data, communicate and to even operate telescopes remotely.Laboratories – while astronomical research is mostly observational (rather than involving laboratoryexperiments), astronomers use laboratories to develop instruments for use on telescopes andspacecraf, and to measure fundamental properties needed to interpret astronomical data.“astro”-Astrology: idea that positions of celestial bodies provide information on personality, humanaffairs (e.g. horoscopes)-Astrophysics: study of the physics of celestial objects-Astrobiology: study of the origin, evolution and distribution of life in the universe-Astrometry: science of measuring the positions of celestial objects such as stars and planets-Astronautics: study of space flights (branch of engineering)A brief History of AstronomyThe study of astronomy goes back to at least the ancient civilisations of Mesopotamia. (present dayIraq). They studied the motions of celestial bodies and they developed the sexagesimal (base 60)system of numbers that we still use today for time and angles (e.g. dividing the hour into 60 minutes,the minute into 60 seconds etc).Many ancient cultures lef structures with “astronomical alignments” built according to the sun.Ancient Greek astronomyThe real beginnings of astronomy can be traced to the philosophers of Ancient Greece. One of theearliest scientists we know of wasPythagoras.Geocentric modelThe Greek philosophers developed what was known as the geocentric model – a model of theuniverse with the Earth at its centre.
One of the earliest models was proposed byEudoxus, a pupil ofPlato. In his model the earth was atthe centre and there were a series of concentric spheres carrying the Sun, Moon and planets, and anouter sphere carrying the fixed stars.Circles on circlesThe Greek philosophers, in particular, believed that celestial objects should move in circular paths,because, according to Plato, the circle was the most perfect figure.