America built the world’s largest telescopes which looked into Deep Space

Posted in America, Astronomy, Historical articles, History, Philanthropy, Science, Space on Wednesday, 8 May 2013

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This edited article about astronomy originally appeared in Look and Learn issue number 247 published on 8 October 1966.

Andrew Carnegie, picture, image, illustration

Andrew Carnegie in 1913

There can be few people who have not heard of the Palomar Reflector, which has a mirror 200 inches across. It is much the most powerful telescope in the world, and it has allowed astronomers to look further into space than they would ever have been able to do without it. It is known as the Hale Reflector, in honour of the man who planned it, but who died before it was completed: George Ellery Hale.

Hale was born in 1868, in Chicago. Astronomy was his boyhood interest, and at the early age of 23 he became famous for his invention of an instrument known as a spectroheliograph, used in studying the Sun. Even as a young man, Hale was far-sighted; he knew that if men were to probe into the depths of the universe, large telescopes would be needed. Unfortunately, such instruments are very expensive indeed. It did not seem likely that any Government would put up the money for a giant telescope, and so Hale looked around for someone who would be prepared to do so.

In 1892 he met Charles Yerkes, a millionaire who owned a large part of the city of Chicago. Yerkes could afford to pay for a large telescope, and he agreed to finance the project. It was decided that the telescope should be a refractor, collecting its light by means of a lens known as an object-glass; the optics were made by Alvan G. Clark, the world’s leading expert. Clark’s object-glass, 40 inches in diameter, turned out to be well-nigh perfect. The telescope was set up in a new observatory outside Chicago, named in honour of Yerkes – with Hale, naturally enough, as its first Director.

Within a few years the Yerkes 40-inch had more than justified the 34,900 dollars spent in building it, but Hale was not satisfied. His motto was ‘More light!’ and he knew that the essential thing was to collect the light from immensely faint, remote stars and star-systems. The 40-inch, powerful though it was, had its limitations, and Hale made up his mind to obtain something better.

There were hopeless difficulties in the way of making an object-glass more than 40 inches across. However, a reflecting telescope collects its light by means of a mirror instead of a lens, and there seemed every chance that a huge mirror could be made – if only the money could be found.

Again Hale was lucky. Andrew Carnegie, one of the few men as wealthy as Charles Yerkes, had set up a financial trust known as the Carnegie Foundation, and this trust agreed to finance a reflector with a 60-inch mirror. George Ritchey, at that time unrivalled as a mirror-maker, took charge of the optical work, and in 1908 the new telescope was ready. It was placed in an observatory on Mount Wilson, a peak in California, from which the observing conditions were particularly good.

Yet, even before then, a larger telescope had been planned. Another millionaire, John Hooker, of Los Angeles, asked Hale whether it would be possible to build a 100-inch reflector. Hale’s prompt answer was “Yes” – and Hooker promised to pay for the mirror. During the construction, Andrew Carnegie visited Mount Wilson, and was so impressed that he offered to meet the cost of the telescope itself.

One evening in November, 1917, Hale and three companions turned the 100-inch reflector to the skies for the first time. They looked at the planet Jupiter – and were shocked. All they could see was a blurred, quivering image. It was a moment of bitter disappointment, but Hale did not give up hope. It was not long after sunset; the mirror had been warm during the daytime, and perhaps it had not ‘settled down’. Hours later he went back to the telescope, and turned it towards the blue star Vega. This time all was well, and Hale knew that he was looking through a telescope more powerful than any in the world.

It is not too much to say that the 100-inch reflector altered many of man’s views of the universe. It could see further into space than any other instrument, and it was widely used. One particularly important discovery was made in 1923 by Edwin Powell Hubble, who had been born in Missouri in 1889 and had joined the Mount Wilson staff in 1919.

Hubble’s main interest was in the objects known commonly as ‘starry nebulae’. Of these, the best-known is the Great Spiral in Andromeda, which is just visible to the naked eye on a clear night. When photographed with a large telescope, it looks rather like a Catherine-wheel made up of stars. At that time, however, nobody knew whether it lay inside or outside our own star-system or Galaxy, simply because nobody had ever been able to measure its distance.

Hubble decided to try, and he studied the Spiral carefully for many months, taking photograph after photograph with the 100-inch reflector. At last he found what he was looking for. Some of the stars in the Spiral turned out to be of a special kind known as Cepheid variables, and Hubble was able to find out how far away they were. Unlike an ordinary star, a Cepheid does not shine with a steady light; it brightens and fades, taking several days to pass from one maximum to the next – and the real luminosity depends upon the period of variation. As soon as Hubble had measured the periods of the Cepheids, he could tell that they were immensely remote, so that the Andromeda Spiral must also be remote. Nowadays we know that its light, moving at 186,000 miles per second, takes over two million years to reach us.

This was the first proof that the ‘starry nebulae’ are, in fact, true galaxies, some of which are larger than the Galaxy in which we live. Hubble continued his work, and confirmed earlier suggestions that almost all the outer galaxies are racing away from us, so that the whole universe is expanding. Moreover, he found that the more distant galaxies recede fastest, and he was able to ‘reach out’ to some 500 million light-years. None of this would have been possible without the help of the great 100-inch reflector.

George Ellery Hale was planning yet another huge telescope, and thanks to his persistence, the decision was made to erect a reflector with a 200-inch mirror. The construction took many years, but in 1948 the telescope was complete, and was brought into use at the Mount Palomar Observatory in California. Since then, it has added greatly to our knowledge of the universe.

Hubble lived to see the Palomar 200-inch completed. Hale, unfortunately, did not; he died at Pasadena, in California, on 21st February, 1938. But he will always be remembered as the man who paved the way for Man’s studies of deep space.

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