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9. Glossary
Angstrom
An angstrom is a unit of length that is equivalent to 10^-10m or 0.1nm. Used mainly to specify the wavelength of radiation.
Electromagnetic spectrum
definition
Emission
The release of a photon from an atom when an electron in the atoms jumps from a higher to a lower energy level.
Interference
Unwanted radio signals received by a radio telescope that originate in human activity rather than natural phenomena.
Light Year
The distance traveled by light, or other electromagnetic radiation,in one tropical year through space. One light year is equivalent to 9.4607 x 10^12 km, or 63,240 astronomical units, or 0.3066 parsecs.
Nebulae
definition
Radiation
Energy propogating in the form of electromagnetic waves or photons.
Radio astronomy
The study of the Universe in the radio part of the electromagnetic spectrum. The radio spectrum ranges from approximately 1mm to 30 meters, almost all of it accessible from ground-based observatores, day and night.
Radio telescope
definition
Star
definition
Wavelength
The distance between successive peaks or troughs of a wave. Wavelengths are equal to the speed of the wave divided by its frequency.


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