Leo, the Lion
Some say that a strange mythological creature, half human and half animal, once represented the summer Sun. Summer was to the Egyptians the most important of the seasons, for the rising of the Nile led to the life-giving floods that in turn led to the promise of bountiful harvests. These people gave over their thoughts to the coming of the season, and their symbolism carried into their astronomy. At this time of year lions from the outlying deserts came down to the Nile Valley to seek relief from the heat. Lions, then, were associated with the coming of summer when the Sun was approaching the constellation we know as Leo. In mid-summer the Sun passed from the stars of Leo and into those of Virgo, the Virgin, representative of the harvest. These two star groups seemed to be in control of the Sun during the most crucial time of the year. And so, as the two signs of summer met, a creature with the body of a lion and the head of a woman was born—the Sphinx.
The stars of Leo were those of a lion to many of the civilizations of ancient times. Not only for the Near East and for the Greeks (whose Leo was the lion who fell from heaven as a meteor, landing in Corinth where he ravaged the land until he was slain by Hercules), but even in the West. These stars were thought to be a puma about to pounce on its prey, according to Peruvian legend. In the middle ages some Christians used this heavenly lion to relate the story of Daniel.
The principal star in the constellation is Regulus, the heart of the lion, or Cor Leonis. This was the first of the four Royal Stars of ancient Persia, with Antares, Fomalhaut and Aldebaran. These stars are separated by about six hours in right ascension, and so they well marked the four quarters of the sky. Regulus is a first magnitude star, although it is surpassed in brightness by 20 other stars. It lies almost exactly on the plane of the ecliptic, so that once a year, on about August 23, it is eclipsed by the Sun. Infrequently it is occulted by the Moon.
Leo serves as the radiant of an important meteor shower, the November Leonids, which are associated with Comet Tempel-Tuttle. The great Leonid shower of 1966 is remembered as having a rate of visible infall in excess of 2000 per minute over a period of a half-hour. There is every reason to expect a particularly strong display from this stream in the year 1999.
There are five Messier objects in Leo, as well as a number of other galaxies and a variety of multiple stars, including doubles Regulus and Algieba (Gamma Leonis). A galaxy hop and a review of double stars are published in separate articles in the April 1997 issue of Sky & Telescope.
Conrad Jung's photo includes a triangle with galaxy NGC 3628 north of M66 (left) and M65. Each shines with a magnitude of about 9½, and all three are about 30 million light-years away.

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