Astronomy Ch 5
| Title: | Astronomy Ch 5 |
| Description: | achromatic lens A telescope lens composed of two lenses ground from different kinds of glass and designed to bring two selected colors to the same focus and correct for chromatic aberration. (p. 82) <br />active optics Thin telescope mirrors that are controlled by computers to maintain proper shape as the telescope moves. (p. 89) <br />adaptive optics A computer-controlled optical system used to partially correct for seeing in an astronomical telescope. (p. 89) <br />alt-azimuth mounting A telescope mounting that allows the telescope to move in altitude (perpendicular to the horizon) and in azimuth (parallel to the horizon). See also equatorial mounting. (p. 89) <br />angstrom A unit of distance. 1 angstrom = 10-10 m. Commonly used to measure the wavelength of light. (p. 79) <br />atmospheric window Wavelength region in which our atmosphere is transparent - at visual, infrared, and radio wavelengths. (p. 80) <br />binding energy The energy needed to pull an electron away from its atom. (p. 95) <br />black body radiation Radiation emitted by a hypothetical perfect radiator. The spectrum is continuous, and the wavelength of maximum emission depends on the body's temperature. (p. 97) <br />Cassegrain focus The optical design in which the secondary mirror reflects light back down the tube through a hole in the center of the objective mirror. (p. 88) <br />CCD See charge-coupled device. <br />charge-coupled device (CCD) An electronic device consisting of a large array of light-sensitive elements used to record very faint images. (p. 90) <br />chromatic aberration A distortion found in refracting telescopes because lenses focus different colors at slightly different distances. Images are consequently surrounded by color fringes. (p. 81) <br />comparison spectrum A spectrum of known spectral lines used to identify unknown wavelengths in an object's spectrum. (p. 91) <br />diffraction fringe Blurred fringe surrounding any image, caused by the wave properties of light. Because of this, no image detail smaller than the fringe can be seen. (p. 83) <br />electromagnetic radiation Changing electric and magnetic fields that travel through space and transfer energy from one place to another; examples are light or radio waves. (p. 78) <br />equatorial mounting A telescope mounting that allows motion parallel to and perpendicular to the celestial equator. (p. 89) <br />eyepiece A short-focal-length lens used to enlarge the image in a telescope. The lens nearest the eye. (p. 80) <br />false-color image A representation of graphical data with added or enhanced color to reveal detail. (p. 90) <br />focal length The focal length of a lens is the distance from the lens to the point where it focuses parallel rays of light. (p. 80) <br />grating A piece of material in which numerous microscopic parallel lines are scribed. Light encountering a grating is dispersed to form a spectrum. (p. 91) <br />interferometry The observing technique in which separated telescopes combine to produce a virtual telescope with the resolution of a much-larger-diameter telescope. (p. 87) <br />light pollution The illumination of the night sky by waste light from cities and outdoor lighting, which prevents the observation of faint objects. (p. 84) <br />light-gathering power The ability of a telescope to collect light. Proportional to the area of the telescope's objective lens or mirror. (p. 82) <br />magnifying power The ability of a telescope to make an image larger. (p. 84) <br />nanometer (nm) A unit of distance equaling one-billionth of a meter (10-9 m). (p. 79) <br />Newtonian focus The optical design in which a diagonal mirror reflects light out the side of the telescope tube for easier access. (p. 88) <br />objective lens In a refracting telescope, the long-focal-length lens that forms an image of the object viewed. The lens closest to the object. (p. 80) <br />objective mirror In a reflecting telescope, the principal mirror (reflecting surface) that forms an image of the object viewed. (p. 80) <br />photon A quantum of electromagnetic energy. Carries an amount of energy that depends inversely on its wavelength. (p. 78) <br />polar axis In an equatorial telescope mounting, the axis that is parallel to Earth's axis. (p. 89) <br />primary lens In a refracting telescope, the largest lens. (p. 80) <br />primary mirror In a reflecting telescope, the largest mirror. (p. 80) <br />prime focus The point at which the objective mirror forms an image in a reflecting telescope. (p. 88) <br />radio interferometer Two or more radio telescopes that combine their signals to achieve the resolving power of a larger telescope. (p. 93) <br />reflecting telescope A telescope that uses a concave mirror to focus light into an image. (p. 81) <br />refracting telescope A telescope that forms images by bending (refracting) light with a lens. (p. 81) <br />resolving power The ability of a telescope to reveal fine detail. Depends on the diameter of the telescope objective. (p. 83) <br />Schmidt-Cassegrain focus The optical design that uses a thin corrector plate at the entrance to the telescope tube. A popular design for small telescopes. (p. 88) <br />secondary mirror In a reflecting telescope, a mirror that directs the light from the primary mirror to a focal position. (p. 88) <br />seeing Atmospheric conditions on a given night. When the atmosphere is unsteady, producing blurred images, the seeing is said to be poor. (p. 83) <br />sidereal drive The motor and gears on a telescope that turn it westward to keep it pointed at a star. (p. 89) <br />spectrograph A device that separates light by wavelengths to produce a spectrum. (p. 91) <br />wavelength The distance between successive peaks or troughs of a wave. Usually represented by the Greek letter lambda. (p. 78) |
| Number of Cards: | 43 |
| Author: | thesuhys13 |
| Created: | 2006-04-30 |
| Tags: | astronomy |
| Private: | No |
| Favorite Count: | 0 |
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