Images Dated 27th June 1996

Illustration of a radio telescope in the night

Radio telescope. Illustration of a radio telescope at night with its dish pointed towards the stars. The telescope's dish reflects incoming radio waves and concentrates them at a single point. A receiver (the black disk) at this position collects the signals and passes them to instruments for analysis. Radio telescopes need a large dish in order to focus the radio waves which have a wavelength of between 1 millimetre and more than 1 kilometre. Radio astronomy is useful because radio waves, unlike light, are not absorbed by the clouds of gas and dust which lie between stars. Astronomical radio sources include quasars, background radiation and galactic cores

© DAVID DUCROS/SCIENCE PHOTO LIBRARY