Describing the universe

The electromagnetic spectrum and telescopes


Astronomy is important to humans because the study of how stars shine can lead to improved or new energy sources on earth. The highest interest of astronomy is the study of it. Astronomers have been able to learn more about the origin of earth and the process involved in the formation of our solar system. Astronomers may learn how to protect us from catastrophes. Astronomical research is supported by federal agencies, such as the National Science Foundation and NASA.


1. Identify the visible and nonvisible parts of the electromagnetic spectrum.

2. Compare refracting telescopes and reflecting telescopes.

3. Explain how telescopes for nonvisible electromagnetic radiation differ from light telescopes.



Electromagnetic spectrum is all of the frequencies or wavelenghts of electromagnetic radiation. The invisible and visible lights both travel in electric and magnetic waves at the same speed. They form of radiation and energy, the energy comes from stars. Both travel in wavelengths and study the universe.

Each wavelength of the visible lights have a different color. Past light through prism, is broken into a set of colors. The shortest wavelengths are blue and violet, the longest wavelengths are red and orange.

The invisible lights needs a special instrument to detect them. The invisible waves include infrared, microwaves, radio waves, ultraviolet rays, x-rays and gamma rays. Waves that are shorter than violet and longer than red, cannot be seen.

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A refracting telescope contains clear lenses, it also bends light. A refracting telescope use lenses to gather and focus light from distant objects. A problem with the refracting telescope is that the lens focuses in different colors of light that are different distances. A reflecting telescope use mirrors to gather and focus light from distance objects. When light enters it is reflected by a large curved mirror to a second mirror. The largest reflecting telescopes are a pair called the Keck telescopes in Hawaii. Both of these telescopes collect electromagnetic radiation. They are both optical telescopes.

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Earths atmosphere acts as a shield against many forms of electromagnetic radiation. A radio telescope detects the invisible radio waves. Ground based telescopes are used to study the forms of radiation, it works best at high elevations. There are telescopes that detect gamma rays, x-rays, and infrared waves. The only way to study many forms of radiation, is from space.

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In space, Earths atmosphere can't interfere with the detection of electromagnetic radiation. The Chandra x-ray observatory makes remarkable clear images using x-rays from space. Spacecrafts contain telescopes and other instruments that have been launched to investigate planets and stars. When replayed in space, this telescope will detect infrared radiation from objects in space.
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