Chap3 - Light_Telescopes

Besides being able to change the angles at which they

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Unformatted text preview: ng able to change the angles at which they observe the sky, these telescopes can be moved by train cars so that the array can detect either wide areas of the sky (when the telescopes are close together, as in this photograph) or small areas with higher resolution (when they are farther apart). The inset shows the traditional secondary mirror assembly in the center of each of these antennas. VISIBLE LIGHT RADIO WAVES The visible light picture was taken by a camera on board a spacecraft as it approached Saturn. The view was produced by sunlight scattered from the planet’s cloud tops and rings. The radio image is a false-color picture, taken by the VLA, and shows radio emission from Saturn at a wavelength of 2 cm. Spitzer Space Telescope (a)The mirror assembly for the Spitzer Space Telescope, showing the 85cm objective mirror. (b)Launched in 2003, this Great Observatory is taking images and spectra of planets, comets, gas, and dust around other stars and in interstellar space, galaxies, and of the large-scale distribution of matter in the universe. (c)Inset: An infrared image of a region of star formation invisible to optical telescopes. Views of the Milky Way’s Central Regions (a)An optical image in the direction of Sagittarius, toward the Milky Way’s center. The dark regions are interstellar gas and dust clouds that prevent visible light from beyond them from reaching us. (b)An infrared image of the same area of the sky, showing many more distant stars whose infrared radiation passes through the clouds and is collected by our telescopes. Nonvisible and Visible Radiation (a)The McMath-Pierce Solar Telescope at Kitt Peak Observatory near Tucson, Arizona, takes visible-light photographs of the Sun. (b)This X-ray telescope was carried aloft in 1994 by the space shuttle. A. X rays penetrate objects they strike head on. B. To focus them, X rays have to be gently nudged by skimming off cylindrical “mirrors.” C. The shapes of the mirrors optimize the focus. The bottom diagram shows how X rays are focused in the Chandra X-ray Telescope. Survey of the Universe in Various Parts of the Electromagnetic Spectrum (a) Visible light (b) Radio waves (c) Infrared radiation (d) X rays (e) Gamma rays Summary of Key Ideas Summary The Nature Of Light Photons, units of vibrating electric and magnetic fields, Photons, all carry energy through space at the same speed, the speed of light (300,000 km/s in a vacuum, slower in any medium). medium). Radio, microwaves, infrared, visible light, ultraviolet, X Radio, rays, and gamma rays, Optics and Telescopes A telescope (1) Gather as much light as possible. Gather (2) Resolves (reveals details) and magnifies an object. (2) . Millers are used in modern telescopes. Earth-based telescopes are being built with active optics Earth-based (control the shape of mirrors) and adaptive optics. These advanced technologies yield resolving power comparable to the Hubble Space Telescope comparable...
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This note was uploaded on 02/03/2014 for the course PHYS 1150 taught by Professor Satoshi during the Spring '08 term at Auburn University.

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