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Chapter 5
Horizons Exploring the Universe 12e
51
Astronomy
Undergraduate 1
10/22/2011

Additional Astronomy Flashcards

 


 

Cards

Term
electromagnetic radiation
Definition
Changing electric and magnetic fields that travel through space and transfer energy from one place to another; examples are light or radio waves
Term
wavelength
Definition
The distance between successive peaks or though of a wave, usually represented by sigma
Term
Frequency
Definition
The rate at which a vibration occurs that constitutes a wave, either in a material (as in sound waves), or in an electromagnetic field (as in radio waves and light), usually measured per second
Term
Photon
Definition
A particle representing a quantum of light or other electromagnetic radiation. A photon carries energy proportional to the radiation frequency but has zero rest mass
Term
Spectrum
Definition
An image or distribution of components of any electromagnetic radiation arranged in a progressive series according to wavelength
Term
nanometer
Definition
One billionth of a meter
Term
angstorm
Definition
A unit of length equal to one hundred-millionth of a centimeter, 1010 meter, used mainly to express wavelengths and interatomic distances
Term
Infrated
Definition
Electromagnect radiation with wavelengths intermediate between visible light and radio waves
Term
Microwaves
Definition
Electromagnetic wave with wavelength, frequency and photon energy intermediate between infrared and radio waves.
Term
Radio Waves
Definition
Electromagnetic wave with extremely long wavelengths, low frequency and small photon energy
Term
Ultraviolet
Definition
Having a wavelength shorter than that of the violet end of the visible spectrum but longer than that of X-rays
Term
Gamma Rays
Definition
Penetrating electromagnetic radiation of shorter wavelength than X-rays
Term
X-rays
Definition
Electromagnetic radiation of high energy and very short wavelength (between ultraviolet light and gamma rays) that is able to pass through many materials opaque to light
Term
Atmoshperic Window
Definition
A narrow range of wavelengths in which the atmosphere absorbs very little of the Earth’s emitted energy.
Term
Refracting telescopes
Definition
A telescope that uses a converging lens to collect light
Term
Reflecting Telescope
Definition
A telescope in which a mirror is used to collect and focus light
Term
Primary Lens
Definition
In a refracting telescope, the largest mirror
Term
Primary Mirror
Definition
A primary mirror (or primary) is the principal light-gathering surface (the objective) of a reflecting telescope.
Term
eyepiece
Definition
The lens or group of lenses that is closest to the eye in a microscope, telescope, or other optical instrument.
Term
focal length
Definition
The distance between the center of a lens or curved mirror and its focus.
Term
Chromatic aberation
Definition
Term
Achromatic Lenses
Definition
A telescope lens compsed of two lenses ground form different kinds of glass and designed to bring two slected colors to the same focuas and correct for chromatic aberrations
Term
Optical telescope
Definition
A telescope that cather and focuses visible light.
Term
Radio Telescope
Definition
A telescope that gathers and focuses electromagentic energy with microwave and radio wavelengths.
Term
Light-Grathering Power
Definition
The ability of a telescope to collect light, proportional to the area of the telescope's objective lens or mirror
Term
Resolving power
Definition
The ability of a telescope to reveal fine detial. Depends on the diameter of the telescope objective
Term
Diffraction fringe
Definition
Blurred fringe surrounding any image, caused by the wave properites of light Becase of this no detail small than the fringe can be seen
Term
Magnifying Power
Definition
The ability of a telescope to make an image larger
Term
Light Pollution
Definition
The illuminationof the night sky by waste light from cities and outdoor lighting , which prevents the observation of faint object
Term
Prime Focus
Definition
The point at which the objective mirror forms an image in relecting telescope
Term
Secondary Mirror
Definition
In a reflecting telescope, a mirror that directs the light from the primary mirror to a focal position
Term
Cassegrain Focus
Definition
The optical design in which the secondary mirror reflects on dramtic and unlikely events, such as collision of two starts to produce our solar system
Term
Newton Focus
Definition
The optical design in which a diagonal mirror relects ligh out the side of the telescope tube for easier access.
Term
Schmidt-Cassegrain focus
Definition
the optical design that uses a thin corrector plate at the entrance to the telescope ture. A popular design for small telescopes.
Term
Sidereal Drive
Definition
The motor and gears on a telescope that turn in westward to keep it pointed at a star
Term
Equatorial Mount
Definition
A telescope mounting that allows motion to parallel to and perpendicular to the celetial equator
Term
Alt-azimuth Mount
Definition
A telescope mounting that allows the telescope to move in altitude and in azimuth (parallel to the horizon)
Term
Active Optics
Definition
A computer-controlled opitical system in a astronmoical telescope used to partially corrent for seeing
Term
Photometers
Definition
An instrument attacted to a scope for the propuse of percisely measuring the brightness of stars or other objects at one or more wavelegnths
Term
Charge-coupled devices (CCDs)
Definition
An electronic device consisting of a large array of light-sensitive elements used to record very faint images
Term
Digitzed
Definition
Information coverted to numerical form for convenitent transger, storage and analysis
Term
Array Dectctors
Definition
A grid of photosensitive dectors for the purpose of recording images.
Term
representational-color
Definition
Describes an image in which information invisible to human eys is represented by visible colors chosen to best convey certian detils Also called false color
Term
False color image
Definition
A reprsentation of a graphical data added or enhanced color to reveal detail
Term
Spectrographs
Definition
Term
Spectral lines
Definition
A  line in a spectrum at a specific wavelegnths to produce a spectrum 
Term
Adaptive Optics 
Definition
A computer-controlled optical system in an astronomical telscope used to partially correct for seeing. 
Term
Laser guide star 
Definition
An artificial star image produced my a laser pointing up into Earth's atmosphere use as reference in adaptive opitics systems 
Term
Interferometry 
Definition
Term
Cosmic Rays 
Definition
 A subatomic particle traveling at tremendous velocity that stikes the Earth's atmosphere from space 
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