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The sun dominates our lives by defining our day, but how much do you know and...
The sun dominates our lives by defining our day, but how much do you know and understand about it? This unit will help you to explore the workings of the brightest star in our universe looking at its structure and the main processes taking place within it. You will also examine the phenomena of sun spots.
At the end of this unit you should:
- know about the electromagnetic spectrum and how it is used to infer properties of sources of radiation;
- know about the range of sizes, distances and motions of objects in the Universe and how they can be measured;
- know about the structure of, and the main processes operating in, the Sun;
- comprehend concepts lying well outside everyday experience, including those that involve very large and very small distances, times, temperatures and energies, and those that are non-intuitive;
- develop the skill of being able to receive and respond to a variety of information sources including textual, numerical, graphical and visual material.
For astronomers, the Sun is fascinating because it is our nearest star. By studying the Sun, they can gain an insight into the workings of the other millions of stars that are visible in the night sky. Learning that the Sun is a star can be a little surprising. After all, the Sun is a brightly glowing, yellow object – so bright that it is dangerous to look at it directly, and so hot that we can feel its radiation warming the whole Earth. Stars, on the other hand, are mere silvery pinpoints of light that are visible only against the darkness of the night sky and with no discernible heating effect on Earth. How can they possibly be the same sort of object? The key to the answer lies in their distances.
In astronomical terms, the Sun is relatively close, being only about 150 million kilometres (93 million miles) from Earth. The stars that are visible at night are much further away: the nearest is about 40 million million kilometres from Earth, and most are much more distant than that. Imagine looking at a glowing light bulb first from very close up and then from a much greater distance. Close up, you would see the shape of the bulb but, from far away, it would be just a point of light.
This unit is from our archive and is an adapted extract from Introducing astronomy (S194) which is no longer taught by The Open University. If you want to study formally with us, you may wish to explore other courses we offer in.
This is an extract from an Open University course which is no longer available to new students. If you found this interesting you could explore more free Physics and Astronomy course units or view the range of currently available OU Physics and Astronomy courses.
Copyright & revisions
Originally published: Monday, 6th June 2011
- Creative-Commons: The Open University is proud to release this free course under a Creative Commons licence. However, any third-party materials featured within it are used with permission and are not ours to give away. These materials are not subject to the Creative Commons licence. See terms and conditions. Full details can be found in the Acknowledgements section.
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