annual meteor shower seen from the earth in July and August. Meteor showers are displays in the sky created by meteors, or pieces of rock that enter the earth’s atmosphere from space.
The Alpha Capricornid meteor shower occurs every year from about July 15 to September 11. The shower’s maximum, or time when the highest number of meteors fall, is usually July 31 and August 1. The maximum rate is about ten meteors per hour. Astronomers have not identified the object responsible for producing the Alpha Capricornids. Since 1953 at least three comets and one asteroid have been suggested, but none perfectly fits the orbit of the meteor stream that causes the shower. The shower is created from the debris in the meteor stream, which becomes visible on the earth when the earth passes through the stream.
The discovery of this meteor shower is attributed to Hungarian astronomer Miklós von Konkoly Thege, who first plotted several meteors emanating from the region of the star Alpha Capricorni on the nights of July 28 and 29, 1871. Alpha Capricorni therefore marks the radiant, or the part of the sky from which the meteors seem to originate, of the Alpha Capricornids. By the end of the 19th century other astronomers’ observations had established that the Alpha Capricornids produce a consistent meteor shower. The meteors of the Alpha Capricornids seem to move more slowly and are brighter than meteors of other showers.
New Zealand amateur astronomer Ronald A. McIntosh found a second, weaker radiant very near the main radiant in 1935. His observations were reinforced in 1956. That year, astronomers at Harvard University determined from photographs of the shower that it might be produced by two or more streams of meteors.