The first purpose-built radio telescope was a 9-meter parabolic dish constructed by radio amateur Grote Reber in his back yard in Wheaton, Illinois in 1937. The sky survey he did with it is often considered the beginning of the field of radio astronomy.
A radio telescope is a specialized antenna and radio receiver used to receive radio waves from astronomical radio sources in the sky in radio astronomy. Radio telescopes are the main observing instrument used in ground-based astronomy.
Radio astronomy studies the radio frequency portion of the electromagnetic spectrum emitted by astronomical objects, just as optical telescopes are the main observing instrument used in traditional optical astronomy which studies the light wave portion of the spectrum coming from astronomical objects.
Radio telescopes are typically large parabolic ("dish") antennas similar to those employed in tracking and communicating with satellites and space probes. They may be used singly or linked together electronically in an array. Unlike optical telescopes, radio telescopes can be used in the daytime as well as at night. Since astronomical radio sources such as planets, stars, nebulas and galaxies are very far away, the radio waves coming from them are extremely weak, so radio telescopes require very large antennas to collect enough radio energy to study them, and extremely sensitive receiving equipment.
Radio observatories are preferentially located far from major centers of population to avoid electromagnetic interference (EMI) from radio, television, radar, motor vehicles, and other manmade electronic devices.
- ↑ Marr, Jonathan M.; Snell, Ronald L.; Kurtz, Stanley E. (2015). Fundamentals of Radio Astronomy: Observational Methods. CRC Press. pp. 21–24. ISBN 1498770193. https://books.google.com/books?id=T54oCwAAQBAJ&pg=PA21.
- ↑ Britannica Concise Encyclopedia. Encyclopædia Britannica, Inc.. 2008. pp. 1583. ISBN 1593394926. https://books.google.com/books?id=ea-bAAAAQBAJ&pg=PA1583&dq=%22radio+telescope%22.
- ↑ Verschuur, Gerrit (2007). The Invisible Universe: The Story of Radio Astronomy (2 ed.). Springer Science & Business Media. pp. 8–10. ISBN 0387683607. https://books.google.com/books?id=bUVQM_BAFlMC&pg=PA8&dq=%22radio+telescope%22+%22radio+receiver%22.