LESSON 1- introduction to astronomy .docx - LESSON 1 –...

LESSON 1 – introduction to Astronomy
What is astronomy?
Astronomy is the scientific study of celestial objects (stars, planets, Galaxies and the universe as a
whole.)
The name derives from the Greek words Astron (“star”) and nomos (“law”)
Tools of astronomy
Telescope – Astronomers use telescopes to observe celestial objects. The quest to study increasingly
distant object and to see them in greater detail has led to larger and larger telescopes (e.g. Keck
telescope)
Spacecraf – the planets and other objects in our own system can be studied using spacecraf that fly
past, orbit or land on them.
Computers – astronomers use computers to analyse their data and to produce mathematical models
that 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 international
collaboration. To share data, communicate and to even operate telescopes remotely.
Laboratories – while astronomical research is mostly observational (rather than involving laboratory
experiments), astronomers use laboratories to develop instruments for use on telescopes and
spacecraf, and to measure fundamental properties needed to interpret astronomical data.
“astro”
- Astrology: idea that positions of celestial bodies provide information on personality, human
affairs (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 Astronomy
The study of astronomy goes back to at least the ancient civilisations of Mesopotamia. (present day
Iraq). 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 astronomy
The real beginnings of astronomy can be traced to the philosophers of Ancient Greece. One of the
earliest scientists we know of was Pythagoras.
Geocentric model
The Greek philosophers developed what was known as the geocentric model – a model of the
universe with the Earth at its centre.

One of the earliest models was proposed by Eudoxus, a pupil of Plato. In his model the earth was at
the centre and there were a series of concentric spheres carrying the Sun, Moon and planets, and an
outer sphere carrying the fixed stars.
Circles on circles
The Greek philosophers, in particular, believed that celestial objects should move in circular paths,
because, according to Plato, the circle was the most perfect figure.