Capricornus, not Capricorn
is the name of the Zodiac constellation that can be found low in the south during evenings in autumn. Astrologers may call it Capricorn, but astronomers do not. Astrology was a way of life, though, until the times when men were able to use more than just their imaginations to study the heavens. And after all, you can call any group of stars anything you like; you can even pay to have stars named whatever you want, and for your money they will put your name in a book in a bank vault in Switzerland, or whatever they say they’ll do. None of these star-naming schemes is official, however, and the names won’t be known to any astronomers. Think carefully before you pay your money, but this is usually an honest way for some people—even legitimate astronomy groups—to sell their imagination.

When, thousands of years ago, the ancient peoples of Babylon and Chaldea looked to a certain portion of the sky they imagined it as akin to the sea. Without many bright stars that region seemed vast as the oceans, stretching beyond their view. The fascination with the sea led to sky stories of wondrous creatures such as the goat-fish that later became the symbol of Capricornus.

Some say the symbolism came from India, where the stars of Aquarius were the first of their zodiac. Its patron god was Varuna, the all-powerful lord of the sky and creator of the stars. He rode through his starry realm on Makara, his fabulous steed, half crocodile and half bird, who was equally adept on the sea as in the air. As Varuna, represented by Aquarius, eventually lost his claim to the sky and became just the god of the oceans, so Makara, represented by Capricornus, also lost his identity and became half fish and half ibex, or wild goat [Capra ibex]. The name Capricornus actually means ‘horned goat’ in Latin.

Sargon, a Babylonian founder of about 2800 BC, left records foretelling the fiery destruction of the world should all the five planets appear at the same time in the sign of Capricornus. Such an event actually occurred, according to Chinese astronomers, in the year 2449 BC. No blazing conflagration was reported.

October is a fine month for observing Capricornus. Find what appears to be a wide arrowhead, pointed downward, by following to the south and east the line of the three bright stars in Aquila.

Capricornus places second to Cancer among the zodiac constellations in faintness. No stars are brighter than third magnitude. The brightest star in the constellation is Deneb Algedi, from the Arabian for ‘tail of the goat.’ Its magnitude is 3.1. About equally bright at 3.2 is Algedi, Alpha Capricorni. This is an optical naked-eye double; the brighter, Alpha-2, is 100 light-years distant, with Alpha-1 about 500 light-years away. The chance alignment places them just over six minutes apart along our line of sight. Each of these stars is multiple. These stars were studied in 1862 by the renowned telescope maker Alvan G. Clark, whose firm made Chabot’s 8-inch refractor in 1883 to the order of founder Anthony Chabot. In 1913 this magnificent telescope was given the name Leah by Chabot Observatory Director Charles Burckhalter.
NGC 6907 is a barred spiral seen nearly face-on. It is just a fuzzy spot (mag. 11.3) in a small telescope.
Image courtesy of Steven Williams, Grove Creek Observatory in Australia.

There are few deep-sky objects of note for small telescopes. M30 is the only Messier object, a globular cluster of magnitude about 7.5 and with a diameter of eleven minutes. Messier discovered the faint cluster in 1764, using a small reflecting telescope of aperture equivalent to two inches. Concluding it to be a nebula, he could not resolve the fuzzy patch into stars; and it was left for Sir William Herschel with his far better optics 19 years later to describe the cluster in detail. The cluster has been found to be about 40,000 light-years away.

The discovery of the planet Neptune is one of the more interesting tales of modern astronomy. Following the discovery in 1781 of Uranus, Herschel’s ‘George’s Star,’ the new planet was found to have an uneven motion. Speculation suggested that yet undiscovered planet was perturbing the orbit in a minute but ‘intolerable’ way. John Couch Adams, an undergraduate at Cambridge, undertook the problem and in 1845, after two years of calculations, sent a prediction of the location of a ninth planet to Astronomer Royal Sir George Airy. Nothing was done to follow up Adams’s work. Meanwhile, Urbain J. J. Leverrier in France independently solved his equations and sent his solution to Johann Galle in Berlin. Galle immediately pointed his telescope to the predicted position. With the help of a graduate student, Heinrich d’Arrest, he found an eighth-magnitude ‘star’ that was not on the best available star map. On closer observation Galle discerned the object to have a small disk. The planet was within a degree of Leverrier’s prediction in Capricornus, near Deneb Algedi. Joyously, Leverrier suggested that the planet be called Leverrier. His second choice, Neptune, was adopted instead. It seems a fitting name for a planet that appears sea-blue in color, and which was first imagined to exist—and then was discovered—in a constellation of the sea.

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