6-4 Exploring Space with Images

Exploring Space – Course 3

My Planet Diary pg. 232Suppose you’re a spy on a dark street, hoping to spot another spy.

How would you see the other spy in the dark? Wear a pair of infrared goggles.

All objects give off radiation that you can’t see. The glowing coils of an electric heater give off infrared radiation, which you feel as heat. Human beings also glow infrared, and with the infrared goggles you can see a green outline of a person in the dark. Some objects in space also give off invisible radiation that we can detect with special telescopes.

In what other situation might you want to wear infrared goggles?

The Electromagnetic Spectrum pg. 232Electromagnetic radiation is energy that can travel through space in the form of waves. Visible light, the light you can see, is just one of many types of electromagnetic radiation. Many objects give off radiation that you cannot see.

The distance between the crest of one wave and the crest of the next wave is called the wavelength. Ex.Visible light has very short wavelengths, less than one millionth of a meter.

The frequency of a wave is the number of waves that pass a given point in a certain amount of time.

If you shine white light through a prism, the light spreads out to make a range of different colors with different wavelengths, called a spectrum.

The electromagnetic spectrum includes the entire range of radio waves, microwaves, infrared radiation, visible light, ultraviolet radiation, X-rays, and gamma rays.

Exploring Space With Images

Properties of the Spectrum

Assess Your Understanding pg. 234I get it! Now I know that the electromagnetic spectrum includes:

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What are Telescopes and How Do They Work? Pg. 235Telescopes are instruments that collect and focus light and other forms of

electromagnetic radiation. Telescopes make distant objects appear larger and brighter. A telescope that uses lenses or mirrors to collect and focus visible light is called an optical telescope. The two major types of optical telescopes are refracting telescopes and reflecting telescopes.

Refracting telescopes use convex lenses to gather and focus light. A reflecting telescope uses a curved mirror to collect and focus light.

The largest optical telescopes today are all reflecting telescopes because, while a mirror can be supported from below, a lens must be supported from the sides so that light can pass through it.

Refracting and Reflecting TelescopesA refracting telescope uses convex lenses to focus light. A reflecting telescope uses a curved mirror to focus light.

Exploring Space With Images

Other Telescopes pg. 236An observatory is a building that contains one or more telescopes.

Because Earth’s atmosphere makes objects in space look blurry, many large observatories are located on the tops of mountains or in space. Just as optical telescopes collect visible light, non-optical telescopes collect and focus different types of electromagnetic radiation. Radio telescopes detect radio waves from objects in space. Other telescopes produce images in the infrared or X-ray portions of the spectrum.

Exploring Space With Images

Where do the Optical, Radio and X-ray telescopes work best?

Assess Your Understanding pg. 237

1a. List the electromagnetic waves, from longest to shortest wavelength.__________________________________________________________________________________________________________________________________________________________________________________________

b. A student of astronomy suggests locating a radio telescope near a radio station. Is this a good idea? Why or why not?

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I get it! Now I know that telescopes are ____________________ _________________________________________________

How Are Planetary Images and Satellite Photographs Made? Pg. 238

Planetary images and satellite photographs are made by collecting visible light and other parts of the electromagnetic spectrum.

Pictures of Earth’s surface based on computer data are called satellite photographs. A satellite image is made of thousands of tiny dots called pixels. Each pixel contains information about the color and brightness of a small part of Earth’s surface. When the image is printed, the computer translates these digitized data into colors.

A picture of a planet taken in visible light or another form of electromagnetic radiation is called a planetary image. Images of planets help scientists understand how the solar system developed.

Saturn in Ultraviolet LightThis planetary image was taken in ultraviolet radiation with the Hubble Space Telescope.

Assess Your Understanding pg. 239

1b. A planetary image is _______________________________

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b. What are the advantages to using planetary images as opposed to drawings? _______________________________

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I get it! Now I know that planetary images and satellite photographs are made by ____________________________

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