Mythology tells us that Cancer was sent by Juno to distract Hercules by pinching his toes while he was contending with the many-headed serpent in the Lernean swamp. Hercules, the legend says, crushed the crab with a single blow, and Juno by way of reward placed it in the heavens.
In Cancer, according to the belief of the Chaldeans, was located the "gate of men," by which souls descended into human bodies, while in Capricornus was the "gate of the gods," through which the freed souls of men returned to heaven.
Hydra, the many-headed serpent with which Hercules contended, is represented by a constellation of great length. It extends from a point just south of Cancer, where a group of faint stars marks the heads, to the south and southeast in a long line of faint stars. It passes in its course just south of Crater and Corvus, the two small star-groups below Leo (see constellations for May), which are sometimes called its riders, and it also stretches below the entire length of the long, straggling constellation of Virgo. At this time we can trace it only to the point where it disappears below the horizon in the southeast. It contains but one bright star, Alphard, or Cor Hydrae as it is also called, standing quite alone and almost due south at this time. Hydra, as well as Lynx and Cancer, contains no noteworthy or remarkable object and consists chiefly of faint stars. Alphard is, in fact, the only bright star that we have in the constellations for this month. It chances that these three inconspicuous star-groups, Lynx, Crater, and Hydra, lie nearest to the meridian at this time, separating the brilliant groups of winter from those of the summer months.
Ursa Major, the Great Bear, and Ursa Minor, the Lesser Bear, or, as they are more familiarly called, the Big Dipper and the Little Dipper, are the best known of all the constellations visible in northern latitudes. They are called circumpolar constellations, which means "around the pole." For those who live north of 40° N. Lat. they never set, but can be seen at all hours of the night and at all times of the year. In fall and winter evenings Ursa Major lies below the pole and near the horizon, and so is usually hidden more or less from view by trees or buildings. It is during the early evening hours of late spring and summer that this constellation is seen to the best advantage high in the sky above the pole. If one looks due north at the time mentioned, it will be impossible to miss either of these constellations.