Astronomical Concepts – Week 1 Introduction

Thursday 13th October was the first week of my new astronomy course at Sydney Observatory. Like the first course I attended earlier this year it is presented by Dr Paul Payne. This course aims to expand on the first and build on some of the main concepts of astronomy, including the solar system, gravity, the theory of relativity, the Sun, stars and quantum theory.

This first week was an introduction to the course and focused on some important concepts: light, gas, nebula, the speed of light, atoms (particularly hydrogen), electrical fields, the electromagnetic spectrum and more. It certainly was a packed 2 and a half hours!


Before we left we had time to observe the night sky through the observatory’s over 140 year old telescope, the oldest in Australia, to see great views of the surface of the Moon and Saturn. The views looked similar to the images below:

This was a great introduction to the course. As usual we had our lecture in the basement theatre and were treated to Paul’s 3D graphics and animations to help illustrate the concepts further. I left with a deeper knowledge of light, in particular how influential the wavelength is. Paul showed us many images of nebulae, including the famous Crab nebula, seen below:


This is probably the most familiar shot of the nebula showing the bright blue, green and orange colours. The image below shows the Crab nebula in a variety of wavelengths. By looking at the nebula in different wavelengths it tells astronomers different information about the star.


X-Rays for example are collected by the NASA Chandra space telescope, amongst other devices. Many things in space emit x-rays, such as black holes, neutron stars, binary star systems, supernova remnants, stars, the Sun and even some comets. Because X-Rays are absorbed by Earth’s atmosphere the Chandra telescope must orbit above it to an altitude of 139,000km. X-Rays are produced in the universe when matter is heated to millions of degrees. These temperatures occur when high magnetic fields, or extreme gravity, or explosive forces, hold sway. Chandra can also trace hot gas from an exploding star or even a black hole. Chandra can help to define the hot , turbulent regions of space to help us understand the origin, evolution and density of the universe. The image of the Crab above in x-ray shows blue colour and in the centre a pulsar can be seen. The star was first discovered in 1942 by Rudolf Minkowski and then later in 1968 the star was found to be emitting its radiation in rapid pulses, becoming one of the first pulsars to be discovered.

This was a great start to the course, highly engaging and interesting as always and I can’t wait for next week!


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