An Early Application Of Automation To Astronomy

by Ruth S. Freitag, Library of Congress

After Piazzi came across the first (and largest) asteroid in 1801, three more were found by Olbers and Harding in the ensuing six years; then nearly four decades elapsed without any further discoveries. However, once the search was resumed by a new cast of characters armed with better star maps, the numbers began to accumulate, beginning in 1845. From 1847 on, not a year passed without the identification of yet another asteroid or two, or six, or eleven. By mid-1873, more than 130 were known. After considering carefully the hardships that dedicated asteroid seekers had to endure, the Bavarian satirical weekly, Fieigende Blätter, announced in its issue of September 19, 1873, the development of an indispensable new accessory:

An Automatic Asteroid Finder

We have succeeded in building an instrument that discovers asteroids, comets, and other unknown celestial bodies by purely mechanical means. The arrangement is as follows: An instrument resembling a telescope, the lens combination of which is designed like that of the camera obscura, is set up facing the sky. This instrument projects all the heavenly bodies within its field of view onto a strip of paper, which stretches between two roScj and is carried along past the focal point of the» strument, by means of a clock drive, at the speed as that of the stars in the field. All the taoJ fixed stars, planets, and asteroids arc shown asdst spots on this paper strip, exactly like a celestial map The rest of the paper is chemically treated in jH a way that the least amount of light falling upc» a spot that is not blackened will set the papers fire. If this rolling chart of the heavens is conectij oriented, the light from a star will fall upon the cog responding black spot on the map; but if there» a star (asteroid or comet) anywhere in the sky tin is not yet shown on the map, i£., not yet discovery a point of light will fall on the chemically prepare! part of the paper; the paper will catch fire, spaib will fall on a fuse treated with powder that c» nects with the touch hole of a small cannon, M a shot will go off. By means of the shot the astn> nomer quietly sleeping in an adjoining room w9 awaken, jump up, rush to the instrument, and,in the field of view of a telescope set up parallel wiA the camera-telescope, he will see the newly discovered star. Klinkerfues, Luther, and all theothB famous asteroid discoverers need no longer expo«

But Olbers, a clever mathematician, offered an intriguing idea in h r that Ceres and Pallas might be fragments of a large planet that d been destroyed by internal explosion or by collision with a comet.

Dosed that astronomers search the two regions in the sky where ^its of Ceres and Pallas came closest to intersecting in the hope f finding other fragments, since an explosion might throw debris in all directions, but the orbits of the fragments would bring them back to the site of the explosion at each revolution. The intersections were in Cetus and Virgo.

On September 2, 1804, Carl Ludwig Harding, an assistant at Schrdter's observatory and himself one of the Lilienthal Detectives, discovered Juno in Pisces, very close to Cetus, and on March 29, 1807, Olbers, taking his own advice, found Vesta in Virgo. It was an embarrassment of riches. All four asteroids were small. Even

Automatic Asteroid Tinder themselves to the night air during frosty winter evenings with their comet-seekers and catch colds and chUls from their tiresome work. Unfortunately it has not yet been possible to bring this epoch-making instrument to the international exhibition. It can be expected, in view of the large number of small planets that are to be found between Mars and Jupiter, that ever/ quarter of an hour a shot will sound, announcing to the earth's entire population the discovery of yet another new asteroid.

¡Translation hy Ruth S Frritag)

Automatic Asteroid Tinder themselves to the night air during frosty winter evenings with their comet-seekers and catch colds and chUls from their tiresome work. Unfortunately it has not yet been possible to bring this epoch-making instrument to the international exhibition. It can be expected, in view of the large number of small planets that are to be found between Mars and Jupiter, that ever/ quarter of an hour a shot will sound, announcing to the earth's entire population the discovery of yet another new asteroid.

¡Translation hy Ruth S Frritag)

Fleigende Blätter, founded in November 1844, poked fun at German social, cultural, and political life with great success during the nineteenth century. Some of its contributing artists, such as Wilhelm Busch and Carl Spitzweg, achieved independent fame. As the years passed, the journal was overtaken by rapidly changing times to which it could not adapt; it expired, finally, in 1944—the only German periodical of its kind to last for a century.

if they were fragments of a larger planet, all of them put together^ all the other pieces that could reasonably be imagined to exist were enough to form one decent-sized primary planet. Today, the total n^ of the asteroid belt (3,700 known asteroids and all those remr'^^

be identified, plus debris and dust) is estimated to amount to lessth» 5 percent of the mass of the Moon. It would take almost 2,000 sti asteroid belts to equal the mass of the Earth. The zone of minor pla^ continues to fragment and reduce itself to dust through collisions ^ it seems never to have contained a planet of major size.

Nevertheless, most astronomers in the early nineteenth century a that Bode's Law was extremely powerful. Why it worked remain^ mystery, but Uranus was found at the distance the law predicted, ag a search of the gap given by the sequence produced the discovery of n, asteroids. Some astronomers even used Bode's Law to suggest that a pla^ lay beyond Uranus.12

Confidence in Bode's Law was great enough so that when John Coud Adams and Urbain Jean Joseph Le Verrier attempted to ra lculate tie 0. istence and position of a planet beyond Uranus, both adopted the rule'i prediction that a trans-Uranian planet would lie at a distance of 3i astronomical units.

Neptune was found where Adams and Le Verrier, using Bode's U* to postulate its distance, had predicted it would be in the sky, but Nep. tune proved to be closer than expected—30.06 astronomical units-n error in the law of 23 percent. And Pluto, whose mean distance frou the Sun is close to where Neptune should have been, is only half the distance that the Law would predict for a ninth planet.

Ironically, the very success of Bode's Law in helping with the disco« of Neptune led directly to its discrediting. Undermined at the peakef its popularity, Bode's Law returned to the status of a curiosity."

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