The discovery of Pulsars in 1967 was for me a great surprise because the research I was then doing was not aimed at discovering a new kind of star. I was then engaged in the branch of Radio Astronomy, which was to do with the study of quasars. In the early 1950s it was discovered that there are galaxies that emit powerful radio waves. Often they are only detectable by the radio waves, not by their optical emission and these radio galaxies were giving us new information about the past history of the universe. Quasars are a particularly active type of radio galaxy in which enormous quantities of energy are produced in a small volume at the centre and understanding them was a key problem. But we did not always know which radio galaxies were quasars. By then there were many hundreds known but radio telescopes were rather poor in those days at imaging radio galaxies and we had little idea how large they were, or whether they contained these active centres which are typical of quasars.

I had an idea that we could use a very well known phenomenon. We are all aware that as we look at stars in the sky they twinkle because of fluctuations in the earth's atmosphere. A discovery that we made at Cambridge in 1964 was that some radio galaxies also twinkle. They twinkle because the sun is blowing gas into space. We call it the solar wind. The solar wind fills our solar system and the irregular volumes of gas leaving the sun pass across the line of sight from the radio telescope to a distant galaxy and cause fluctuations in those radio signals. So some radio galaxies twinkle rather like stars twinkle but only if they are very small in angular size. If they appear as it were as ping pong balls in the sky, they would twinkle. Larger radio galaxies would not twinkle. I was planning to use this phenomenon to know which radio galaxies were quasars.

Unable to display preview. Download preview PDF.

Authors and Affiliations

1. Cavendish Laboratory, CB3 0HE, Cambridge, UK

   Antony Hewish

Editors and Affiliations

1. International Institute for Applicable Mathematics & Information Science, B.M. Birla Science Centre, Adarshnagar, Hyderabad, India

   B. G. Sidharth

Reprints and permissions

© 2008 Springer Science + Business Media B.V

Policies and ethics