Photo of early radio telescope model via NAAPO
In 1890, an electrical engineer working for Thomas Edison by the name of Arthur Kennelly wrote a letter to the director of the Lick Observatory. He had described an interesting experiment being undertaken by Edison that may have been the first radio telescope — forty years before its official invention, interestingly enough.
According to historical record as we know it, the first radio telescope was built in 1931 by Karl Jansky, an ingineer working for Bell Laboratories, with the intention of discovering the source of interference transmissions. His investigation led him to conclude that the origin of the interference transmissions was, in fact, the Milky Way. Five years later, amateur astronomer Grote Reber applied this technique in the first application of a new branch of astronomy that became known as radio astronomy.
Still, there are tantalizing hints that its birth may have come almost 40 years before.
In his letter about Edison to the director of Lick, Kennelly said the inventor had turned his mind to solar physics. Along with the electromagnetic disturbances we receive from the Sun,” he wrote, “which, of course, you know we recognise as light and heat” Edison had decided that it was “not unreasonable to suppose there will be disturbances of much longer wavelength.”
If this were to prove true, Kennelly said, “we might translate them into sound.”
Edison’s plan was to use a huge mass of iron ore. Around this hunk of metal, he would erect a series of wooden poles, and from these poles would be a cable consisting of seven carefully insulated wires, the terminals of which would be attached to a telephone or similar apparatus. “It is then possible,” Kennelly wrote, “that violent disturbances in the Sun’s atmosphere might so disturb either the normal electromagnetic flow of energy we receive, or the normal distribution of magnetic force on this planet, as to bring about an appreciably great change in the flow of magnetic induction embraced by the cable loop.”
Edison had suspected that such electromagnetic disturbances would be associated with sunspot activity and hoped that Lick Observatory would be able to provide information as to just when these occurred, since Edison and Kennelly would not be able to establish a connection “unless we have positive evidence of coincident disturbances in the corona.”
Unfortunately, there is no evidence one way or the other whether Edison ever carried out the experiment. If he had, it probably wouldn’t have worked. Edison’s proposed apparatus would have been very insensitive, capable of detecting only very long wavelengths—and the ionosphere prevents such long waves from reaching the earth’s surface. Ironically, it was Kennelly who went on to co-predict the existence of the Heaviside Layer, which accounted for this effect.
Article originally published here.
via Jean-Francois Hibbert’s Page http://jeanfrancoishibbert.org/2013/09/24/thomas-edison-almost-invented-the-radio-telescope/