The universe has always been an object of curiosity for mankind. The phenomena in the sky were interpreted by our ancestors in ancient days as signs which governed their destiny. Astronomy took a giant step and became a science at the beginning of the 17th century, with the invention of the first astronomical instrument. Radioastronomy which consists of detecting radio signals from the universe was born only recently. The first radio emission of extraterrestrial origin came from the Milky Way and was discovered accidentally in 1932 by Karl Jansky while working at the Bell Telephone Laboratories. The radio signals from the sun, the closest star, were detected only a decade later. After these serendipitous discoveries, radioastronomy expanded rapidly after the Second World War, thanks to the development of more and more sophisticated antennas and receivers. Radio emission as weak as 10-12µW, coming from remote celestial objects can be detected by large modern radio telescopes which provide both high angular resolution and sensitivity.
KeywordsBrightness Temperature Radio Source Interstellar Medium Radio Telescope Radio Galaxy
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