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Cosmic Search Vol. 1, No. 1

Glossary


Astronomical Unit:
A unit of length equal to the distance of the earth from the sun, about 150 million kilometers.

Bandwidth:
The wavelength or frequency range to which a receiver responds. Bandwidths can be described as narrow or wide, according to their range.

Big Bang:
The beginning event in the Universe. The explosion of this primordial fireball some 15 billion years ago caused the initial outward expansion of gas and dust which formed the universe. CETI: An acronym for Communication with Extra-Terrestrial Intelligence.

Civilization:
According to the Russian astrophysicist Kardashev, civilizations can be classified according to their energy outputs as follows:

Type I:
A civilization capable of using all of the energy falling on its planet from its "sun" for interstellar communication. (For us this would be equal to 10,000 times the present total energy consumption by mankind for all purposes.) Hence, we are more like a "Type O" civilization.

Type II:
A civilization capable of using the total energy output of its "sun" for interstellar communication.

Type III:
A civilization capable of using the total energy output of our galaxy for interstellar communication.

Dipole:
A configuration with a plus and minus charge. An antenna one-half wavelength long.

Doppler Shift:
The resulting frequency change caused by the relative motion along a line of sight between two observers.

Exobiology:
The study of extraterrestrial life forms.

Fourier Analysis:
The decomposition of a signal into its simplest harmonic curves (sines and cosines). Galaxy: A large system of stars. Our galaxy, the Milky Way, is a spiral galaxy containing some 100,000 million stars, 100,000 light years in diameter and 10,000 light years thick.

Gigahertz:
A unit of frequency equal to 1,000 million hertz.

Hertz:
A unit of frequency equal to one cycle per second.

Hydrogen:
The most abundant element in the universe. It radiates naturally at a wavelength of 21 centimeters.

Light Year:
The distance traveled by light in one year, about 1 0 trillion kilometers.

Light (speed of):
In empty space: 300,000 kilometers per second.

Maser:
A sensitive amplifying device employing energy jumps of atomic particles.

Megahertz:
A unit of frequency equal to one million hertz.

Parametric amplifier:
A sensitive amplifying device which employs the properties of non-linear elements.

Redshift:
A shift toward the longer wavelengths of the optical spectrum due to recessional velocity (the Doppler effect).

SETI:
An acronym for Search for Extra-Terrestrial Intelligence.

Zeeman effect:
A broadening or splitting of radiation from a substance into several wavelengths because of the presence of a magnetic field.


Copyright © 1979-2004 Cosmic Quest, Inc., Big Ear Radio Observatory and North American AstroPhysical Observatory.
Webpage originally designed by Point & Click Software, Inc.
Updated by Jerry Ehman.
Last modified: September 21, 2004.

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