Visible light is just a small part of the spectrum of electromagnetic radiation. At longer wavelengths than the red and infrared are the radio waves, and they are detectable with radio telescopes. However, it is very difficult to observe fine detail in objects using radio telescopes; this difficulty stems from the long wavelength of the light. Put in astronomical jargon, radio telescopes suffer from limited resolution compared to optical telescopes.

Martin Ryle, born in England on September 27, 1918, found a way to greatly improve radio astronomy. He had worked with radar during World War II and afterward took up radio astronomy at Cambridge University when the discipline was still in its infancy. Visual telescopes had been in use for over 300 years, but radio astronomy had just come into being in 1932 when Karl Jansky built a simple antenna. In 1937, Grote Reber made a great improvement when he built the first...