Astronomy: The Science of the Heavenly BodiesTodd, David P. (David Peck)
History
Astronomy: The Science of the Heavenly Bodies
Todd, David P. (David Peck)
Astronomy
Quite by accident a discovery of one of the guessed-at small planetary
bodies was made, on January 1, 1801, in Palermo, Sicily, by Piazzi, who
was regularly occupied in making an extensive catalogue of the stars.
His observations soon showed that the new object he had seen could not
be a fixed star, because it moved from night to night among the stars.
He concluded that it was a planet, and named it Ceres (1), for the
tutelary goddess of Sicily.
Other astronomers kept up the search, and another companion planet,
Pallas (2) was found in the following year. Juno (3) was found in 1804,
and Vesta (4), the largest and brightest of all the minor planets, in
1807. Vesta is sometimes bright enough when nearest the earth to be seen
with the naked eye; but it was the last of the brighter ones, and no
more discoveries of the kind were made till the fifth was found in 1845.
Since then discoveries have been made in great abundance, more and more
with every year till the number of little planets at present known is
very near 1,000.
The early asteroid hunters found the search rather tedious, and the
labor increased as it became necessary to examine the increasing
thousands of fainter and fainter stars that must be observed in order to
detect the undiscovered planets, which naturally grow fainter and
fainter as the chase is prolonged. First a chart of the ecliptic sky had
to be prepared containing all the stars that the telescope employed in
the search would show. Some of the most detailed charts of the sky in
existence were prepared in connection with this work, particularly by
the late Dr. Peters of Hamilton College. Once such charts are complete,
they are compared with the sky, night after night when the moon is
absent. Thousands upon thousands of tedious hours are spent in this
comparison, with no result whatever except that chart and sky are found
to correspond exactly.
But now and then the planet hunter is rewarded by finding a new object
in the sky that does not appear on his chart. Almost certainly this is a
small planet, and only a few night's observation will be necessary to
enable the discoverer to find out approximately the orbit it is
traveling in, and whether it is out-and-out a new planet or only one
that had been previously recognized, and then lost track of.
Public-domain text, read in full here on John Shaqi.
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