An Epoch of Discovery

It wasn't until the 1960s that the bond with "teal" astronomers began to be forged on a large scale, following stunning new discoveries made possible by enormous improvements in receiver technology and the construction of large reflector-type radio dishes and interferometers with ever greater baselines, the distance between their individual dishes. These contributed to the radio astronomer's ability to measure radio source positions with greater accuracy, sufficient to force the attention of the general community of optical astronomers. The days when an old-timer at a meeting of the Royal Astronomical Society in London was overheard to ask "What is this new-fangled wireless astronomy?" were past.

The 1960s also saw the transformation of radio astronomy into a "big science," which brought with if a remarkable period of exciting new discovery. Research at the forefront was, however,

... only open to those groups with sufficient expertise to develop the complex techniques required and with sufficient repute to attract extensive financial support from government and from industry.

Radio astronomy growth during this phase largely bypassed the United States. It was only in the mid-1960s, following the Sputnik panic that urged greater emphasis on science, that US radio astronomers began to catch up.

The 1960s and early 1970s saw the discovery of quasars, pulsars, radio source polarization, complex interstellar molecules, interstellar masers, radio stars, bipolar flows, radio jets, and extragalactic molecules, and the first measurement of the interstellar magnetic field strength. Those years also saw the solidifying of the theoretical understanding of the emission mechanisms involved in thermal and nonthermal radio sources (Appendix A.4), while explanations for the maser mechanism as well as pulsar radiation (Chapters 7 and 8) were quick to develop.

According to Edge and Mulkay;

Stage three is characterized by a growing concern with astrophysical problems, arising hugely from the major discoveries of quasars and pulsars and from the advent of new approaches like those of ultra-violet, X-ray, and infra-red astronomy. By this stage radio methods have become an established part of astronomy.

By the mid-1960s and certainly at the end of that decade, it was firmly demonstrated that the universe was not as quiet as had long been assumed. The universe is wracked with violence on all scales ranging from exploding stars to exploding galaxies and quasars and even to violence on the scale of the universe itself, the Big Bang.

From the point of view of growth, and availability of funds to drive this growth, the period 1960-1975 might be called the Golden Age of radio astronomy. That was also when radio astronomical terms such as quasar and pulsar entered the mainstream vocabulary.

Whenever someone hears that 1 am a radio astronomer, and after they have passed through the phase of confusing this with some form of astrology, I am often asked "How far can the telescope see things?" Bearing in mind that radio telescopes are not something you can see through, we nevertheless use the colloquialism of "seeing" radio waves. That is part of the jargon of the trade. We can't say we listen to radio signals from space either, because there is nothing to hear that the human ear can detect against the background "noise" produced by the radio receivers attached to the radio telescope. (It is a sign of the times that a radio telescope is best described as a large satellite dish!) Instead, we look at the output of a computer program that converts the radio signals generated by a host of interesting physical events in the depths of space into numbers or maps of what those objects would look like if you could literally "see" radio signals.

As regards the question "How far can a radio telescope see?" 1 usually respond that they can "see" farther than the Hubble Space telescope, very nearly to the beginning of the universe. The reason is simple. Virtually every radio telescope ever constructed, if equipped with a suitably sensitive receiver, could, in principle, detect the faintest of whispers left over from the Big Bang (Chapter 13), provided reception is not swamped by terrestrial signals (interference) that might overwhelm anything that reaches those dishes from outer space.

References

1. K. Kellermann and B. Sheets (eds.h Serendipitous Discovery in Radio Astronomy, National Radio Astronomy Observatory. Green Bank, WV, 1983.

2. D. O. Edge and M. J. Mulkay, Astronomy Transformed, Wiley-lnterscience, London.. 1976.

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