Abstract
THE closest celestial object to the earth is our own moon, the mean distance of which is roughly a quarter of a million miles. No other object is known to have approached nearly so closely to us without falling to the earth's surface. The record for a close approach had been held by an eighteenth-century comet, discovered in 1770 by Lexell, which was distant only 1 40 million miles from the earth's surface. Some recently discovered minor planets have ceme fairly close to the earth; Amor, discovered in 1932, came within ten million miles, and 1932 HA within six million; but all records, cometary or planetary, have been broken by the minor planet 1936 CA discovered by Delporte at Uccle on February 12 of this year. This tiny object passed within 1-38 million miles of the earth on February 7. It has proved extremely difficult to determine the elements of this minor planet's orbit, and in particular, the period is hard to ascertain, so that it is difficult to predict the next approach. Since the object passes close to several major planets, large perturbations in its orbit may be expected. It is not impossible (though the possibility is remote) that the object may ultimately collide with the earth; there is a wide margin of safety at present. The view has been expressed that this object may belong to the same group as the great meteorites of Siberia and Arizona. On the other hand, far from colliding with a major planet, the object may eventually be thrown into a very long orbit with a very long period, or even ejected from the planetary system altogether. Should a collision occur, the damage will be very severe over an area having a diameter of a hundred miles or so, judging by the Siberian meteorite.
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A Close Approach to the Earth. Nature 137, 732–733 (1936). https://doi.org/10.1038/137732d0
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DOI: https://doi.org/10.1038/137732d0