Download Using Technology To See Beyond The Visible

Using Technology to see beyond the visible
Not all information from stars can be seen. Optical telescopes give us information
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based on visible light. However, objects in space, such as stars and galaxies, also
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emit radio waves, infrared (heat) waves, and x-rays. These are all forms of
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electromagnetic energy. This energy travels at the speed of light, 300 000 km/s,
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but has different wavelengths and frequencies from those of light. Wavelength is a
measurement of the distance from one point on a wave (such as the crest) to the
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same point on the next wave. Frequency is the number of waves that pass a single
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point in one second.
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Energy with a high frequency has a short wavelength. Gamma rays, for instance,
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have a high frequency and a very short wavelength (less than a millionth of a
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centimeter). Radio waves have a low frequency, but wavelengths that can be
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several kilometers long.
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The visible light we see all around us occupies a small section of the entire
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electromagnetic spectrum, which covers the whole range of electromagnetic
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energy. Visible light has a wavelength measured in micrometer. One micrometer
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is 1 millionth of a metre.
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Science in action 9 Grade 9 page 440