The branch of astronomy devoted to making
observations of the universe in radio waves
using radio telescopes, radio interferometers,
and other types of antennae. Radio astronomy began through the pioneering
work of Karl Jansky and Grote Reber.
|A radio image of Cassiopeia
A hangs above the National Radio Astronomy Observatory's Very
Large Array. The picture, by Michael Bietenholz using data from
the NRAO and Rick Perley, was a prize-winner in the NRAO/AUI Radio
Astronomy Image Awards.
Among the processes by which astronomical bodies emit radio waves are:
Among the important radio sources that have
been probed by radio astronomers are quasars,
radio galaxies, the center of the Milky
Way Galaxy, pulsars, masers
and other emission by interstellar molecules including the 21-centimeter
line of neutral hydrogen, solar flares,
sunspots, and the cosmic
- Thermal radiation from solid
bodies such as the planets.
- Thermal radiation, or bremsstrahlung,
from hot gas in the interstellar medium.
- Synchrotron radiation
from relativistic electrons in weak magnetic fields.
- Spectral line radiation from atomic and molecular transitions that
occur in the interstellar medium or in the gaseous envelopes around
- Pulsed radiation from fast-spinning neutron
stars with powerful magnetic fields.
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