What Use Is Astronomy
J.B.S. Haldane

THERE has been an Astronomer Royal for two hundred and fifty years, but there is no Physicist Royal nor Bacteriologist Royal, although during the last fifty years physics and bacteriology have been of greater service to the State than astronomy. And the taxpayer may sometimes be tempted to ask what return he gets for the money spent on Greenwich Observatory. There cannot be the faintest doubt of its value during its first two centuries of existence. Navigators depended on observations of the sun, moon, and stars to a far greater extent than now. There were no lighthouses to give them their position, no accurate charts, no wireless, and above all, a sailing ship was vastly more likely than a steamer to deviate from its intended course. Accurate astronomical tables were not only required for the purposes which they now serve; but until Harrison invented the chronometer, the only satisfactory method of obtaining the time at sea was by observing the occultation or covering of stars by the moon or of his satellites by Jupiter. And so Greenwich Observatory played a very important part in the foundation of the British Empire.

But the nautical almanac could now be kept up to date (or rather three years ahead) by a few calculators whose results were checked by a single telescope; and the large majority of astronomers now interest themselves not so much in the motions of the sun, moon, and planets, as in the distances, composition, and temperatures of the fixed stars, or in the structure of the sun, and their observations are certainly of no use to navigators.

But that is not to say that the Astronomer Royal is not earning his salary. For the greatest benefits of astronomy have been indirect and unperceived. I fear that few racegoers as they take out their field-glasses bless the name of Galileo, who made the first at all powerful telescope in order to observe the stars. Nor does the engineer or surveyor always remember that both trigonometry and logarithms were invented by astronomers to aid them in their calculations. Again, common sense tells us that we see things as they are. It was an astronomer who, by observing that the eclipses of Jupiter' s moons were later than theory demanded when they were farther away from the earth, showed that we see things as they were, and that light moves with a finite speed. When the same speed turned up in connection with electricity, Clerk Maxwell predicted electro-magnetic waves. Herz produced them, and Marconi put them at the service of mankind.

Modern astronomy, among other things, has given birth to spectroscopy. The spectroscope which analyses a beam of light into its component colours is the only means we have for investigating the composition of the stars, and it is largely for this reason that its use was developed. And it has turned out as practical an instrument as the telescope. It has been used in the analysis of minerals and the detection of poisons; indeed, it has played its part in hanging several murderers. It is now throwing so much light on the structure of atoms and molecules that we may confidently hope that our grandchildren will learn a chemistry based on half a dozen simple laws instead of being compelled, like ourselves, to memorize the idiosyncrasies of the various elements and compounds.

But stellar spectroscopy has done much more than merely give the chemist a new method. It enables him to study matter under conditions of temperature and pressure which he cannot attain in the laboratory. If you want to know how a gas behaves at a pressure of a hundred thousandth of an atmosphere you can watch it in a vacuum tube in the laboratory; if you desire to investigate it at a hundredth of that pressure, the astronomer will direct your telescope to a suitable nebula. And seeing that electric light bulbs, X-ray tubes, the triode valves used in wireless, and the luminous tubes of sky signs all contain gas at low pressure, it is useless to describe the investigation of its properties as unpractical.

Astronomy began as the handmaid of astrology when men believed that the study of the heavenly bodies would enable them to predict events on earth. The old astrology is dead, but a few earthly phenomena have been found to depend on the sun and moon. To predict the height of the tides within an inch may seem an unnecessary refinement, but that inch may mean a saving of a hundredth of one per cent. in the expenses of a great port, and therefore be amply worth while.

And weather does to some slight extent depend upon sunspots which appear according to a definite law. Attempts to predict the yields of crops by this method have met with small success, but the number of rabbits and hares in Northern Canada depends on that of sunspots to a remarkable degree. Every ten or eleven years the number of hares increases enormously, and a sudden pestilence then wipes them out. The next year there is great hunger among the lynxes and foxes which feed on them, and many more than usual are caught. It is quite safe to prophesy that about 1926 there will be an abnormally large catch of red and cross foxes in Canada. And if the women voters can persuade the Government to appoint a national fur council, perhaps the price may come down.

End of What Use Is Astronomy by J.B.S. Haldane