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SAGITTA
The Arrow
Sagitta - Celestial Atlas by Alexander Jamieson - 1822
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Sagitta is the third smallest constellation in the sky. It is also one of the oldest, being recognized by most cultures worldwide as an arrow for as long as arrows have been around.
The myths and stories surrounding the arrow in the sky are many. It is often associated with other constellations such as Hercules, Aquila, Sagittarius, and others. Some say it is aimed at Cygnus, although it is certainly not aimed well at the giant swan. Some even say it is aimed at Aquila, making it some sort of strange double pointed arrow, also not aimed very well. If you trace the arrow backwards, it seems to originate from the constellation Ophiuchus, a healer who dealt with snakes, not arrows. When you trace it forward, it appears to be aimed at the winged horse, Pegasus, who had many colorful adventures, none of which had anything to do with an arrow. I like to think of the arrow the way many ancient Greeks and Romans did: as the arrow of Eros, the god of love and passion. Eros was the son of Aphrodite (Venus), and Ares (Mars). To the Romans he was known as Cupid, and those who were struck by one of his arrows were filled with romantic love, a legacy of his mother Aphrodite, the goddess of love. Unfortunately the romances did not always go well, for Eros was also the son of Ares, and Ares was the god of war.
Sagitta has only one named star. It is called "Sham" which is Arabic for the arrow. Unconventionally, it is not the brightest star in the constellation. It is only the third brightest, and represents only one of the arrow's feathers, leading to speculation that the star was brighter in ancient times. It is a G1 giant yellow star 610 light years away, with a magnitude of 4.37.
Sagitta has one Messier object: M71, a globular star cluster. With a magnitude of 6.1, it is difficult to see with the naked eye unless the sky is very dark, but it is a fine sight in a backyard telescope. M71 is 27 light years across, one of the smallest and sparsest of the 150 or so globular star clusters that surround our Milky Way galaxy. It is also one of the closer globular clusters, at a distance of 13,000 light years.
Sagitta has one known star with a planetary system. The star is HD 231701, at a distance of 354 lightyears, and with a magnitude of 8.97, which places it well outside the limits of naked eye visibility. So far one planet the size of Jupiter has been discovered orbiting very close to this star, about half the distance of Earth from the Sun. For more information on exoplanets, visit NASA's Planet Quest.
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