The discovery of pulsars in 1967 was one of those lucky accidents that sometimes happen in scientific research. At that time, it can’t be said that Anthony Hewish and his colleagues were looking for pulsars when they were actually studying quasars – extremely luminous radio galaxies located far beyond the confines of the Milky Way – when the first pulsar suddenly placed it presence upon their records.
So, let’s take a look at this extremely fortunate and sudden twist of fate.
Going Back to the 20th Century
It all began in 1964 when a team of astronomers noticed that certain radio galaxies, noted for their tiny angular extent, exhibited rapid and irregular variations of intensity. This phenomenon was very similar to the “twinkling” of visible stars and they eventually learned that it was caused by clouds of hot gases ejected from the sun.
These clouds take part in the violent and continual outflow of material from the sun known as the “solar wind.” Because the clouds are so hot, electrons are stripped from the atoms and the gas becomes a mixture of electrically charged particles. Therefore, radio waves are deflected slightly as they pass through these clouds and as a result, originally parallel rays from a distant radio galaxy become entangled as they traverse the solar system. It is this effect that causes the radio galaxies to “twinkle.”
But, the odd in here was that only very compact sources like quasars are subject to such “twinkling” while ordinary radio galaxies tend to average out the fluctuations.
The astronomers then thought that this “twinkling effect” would be an excellent method of finding, among the several thousand radio galaxies that have been charted, those galaxies that actually are quasars.
And, so in 1966, they started to build a radio telescope especially designed for this purpose.
However, observations with this new radio telescope only began in 1967 and it took a whole week to scan a large fraction of the sky to investigate how the radio “twinkling” of the quasars varied in strength as the sources were studied at different angular distances from the sun.
It started in August when an odd-looking tracing was recorded on which a radio source had apparently been “twinkling” in the middle of the night. This was unusual because intensity variations caused by the solar gas are always very small when observations are carried out in directions away from the sun.
Initially, they did not really believe that the signals were genuine because radio telescopes often pick up terrestrial interference of one kind or another. But when the strange signals kept reappearing, it was plain that the phenomenon could no longer be ignored.
The next phase included obtaining a detailed recording, using a much faster chart speed in order to make a closer inspection of the signals. It was not until late November that they discover the signals from this mysterious source were in the form of short-duration pulses spaced at regular intervals of about one and one-third seconds.
Several inspections were carried out to convince the astronomers that they were not being tricked in some way. But, of course, the same signals were always there and in December, the source flared up in intensity and produced some really beautiful pulses.
In Contact With the “Twinkling” Phenomenon
The period that followed was one of pure and intense excitement.
From their discoveries, astronomers knew that the object was far beyond the solar system. They also knew that the body had to be small – probably about the size of the earth – as a large body simply could not emit a short-duration pulse because radiation leaving different parts of its surface will arrive at different times.
This could only mean one thing: They came into contact with intelligent beings of the galaxy and this could not be ignored.
Naturally, after going further with their observations, they came to a point where they felt confident enough to announce their findings to the scientific community.
The news of this interesting discovery triggered an intensive period of activity and the truth about pulsars eventually led to a new and fascinating chapter in the history of astronomy.
Today, the scientific community still holds a range of questions regarding pulsars. And, no one really knows when or how these questions would be answered. But, one thing is for sure, the answer is found high above.