قراءة كتاب A Field Book of the Stars

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A Field Book of the Stars

A Field Book of the Stars

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دار النشر: Project Gutenberg
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src="@public@vhost@g@gutenberg@html@files@20769@20769-h@images@img5_th.jpg" alt="Ursa Major" title="Ursa Major" tag="{http://www.w3.org/1999/xhtml}img"/> URSA MAJOR


URSA MINOR (er´-sa mi´-nor)—THE LITTLE BEAR. (Face North.)

Location.—The two pointer stars in Ursa Major indicate the position of Polaris, the North Star, which represents the tip of the tail of the Little Bear, and the end of the handle of the "Little Dipper." In all ages of the world, Ursa Minor has been more universally observed and more carefully noticed than any other constellation, on account of the importance of the North Star.

Polaris is a little more than 1¼° from the true pole. Its light takes fifty years to reach us.

A line joining β Cassiopeiæ, and Megres, in Ursa Major, will pass through Polaris.

At the distance of the nearest fixed star our sun would shine as a star no brighter than Polaris which is presumably about the sun's size.

Polaris revolves around the true pole once in twenty-four hours in a little circle 2½° in diameter. Within this circle two hundred stars have been photographed.

The North Star is always elevated as many degrees above the horizon as the observer is north of the equator.

Compare the light of the four stars forming the bowl of the "Little Dipper," as they are each of a different magnitude. A standard first-magnitude star is 2½ times brighter than a standard second magnitude star, etc.

URSA MINOR URSA MINOR


GEMINI (jem´-i-ni)—THE TWINS. (Face West.)

Location.—A line drawn from β to κ Ursæ Majoris and prolonged an equal distance ends near Castor, in Gemini. Gemini is characterized by two nearly parallel rows of stars. The northern row if extended would reach Taurus, the southern one Orion. Note the fine cluster 35 M. Herschel discovered Uranus in 1781 a short distance southwest of it. Two wonderful streams of little stars run parallel northwest on each side of the cluster. Where the ecliptic crosses the solstitial colure is the spot where the sun appears to be when it is farthest north of the equator, June 21st. Castor is a fine double for a telescope, and Pollux has three little attendant stars. An isoceles triangle is formed by Castor, Aldebaran in Taurus, and Capella in Auriga. There is a record of an occultation in Gemini noted about the middle of the fourth century b.c.

The Arabs saw in this group of stars two peacocks, the Egyptians two sprouting plants, and the Hindus twin deities, while in the Buddhist zodiac they represented a woman holding a golden cord. Since classic times, however, the figure has always been that of human twins.

At the point indicated near θ a new star was discovered by Enebo in March, 1912. It attained a maximum of about magnitude 3.5 and has at this writing waned to the eleventh magnitude.

GEMINI GEMINI


AURIGA (â-ri´-ga)—THE CHARIOTEER. (Face Northwest.)

Location.—A line drawn from δ to α Ursæ Majoris, and prolonged about 45°, ends near the bright Capella, in Auriga, a star of the first magnitude, and one of the most brilliant in the heavens. It is unmistakable, having no rival in brightness near it. Auriga is a beautiful and conspicuous constellation. It is characterized by a clearly defined pentagon. Note the three fourth-magnitude stars near Capella known as "The Kids." The star β is common to Auriga and Taurus, being the former's right foot and the latter's northern horn. The field within the pentagon is particularly rich in clusters. Capella forms a rude square with Polaris, ε Cassiopeiæ, and ο Ursæ Majoris, and forms an equilateral triangle with Betelgeuze in Orion, and the Pleiades in Taurus.

A line from θ to α Aurigæ prolonged about 20° ends near α Persei.

Capella is visible at some hour of every clear night throughout the year. Of the first-magnitude stars it is nearest to the Pole, and it rises almost exactly in the northeast.

To the Arabs Capella was "The Driver," because it seemed to rise earlier than the other stars and so apparently watched over them, or still more practically as "The Singer" who rode before the procession cheering on the camels, which last were represented by the Pleiades.

AURIGA AURIGA


CANCER (kan´-ser)—THE CRAB. (Face West.)

Location.—Cancer lies between Gemini and Leo. A line drawn from Nath in Auriga to Pollux in Gemini, and prolonged about 15°, ends in Præsepe, the Manger, the great star cluster in Cancer, which is also called "The Bee Hive." It contains 300 stars. The stars γ and δ are called the Aselli—the ass's colts feeding from the silver manger.

The star β lies about 10° northeast of Procyon. Acubens, α lies on the same line the same distance beyond β. These two stars form the tips of the inverted "Y" which distinguishes Cancer.

An imaginary line from Capella through Pollux will point out Acubens. Close to it are two faint stars. The Bee Hive lies within an irregular square formed by γ, δ, η, and θ, and looks like a nebula to the naked eye.

In June, 1895, all the planets except Neptune were in this quarter of the heavens, and Halley's comet was in this constellation on its first appearance in 1531.

The dimness of γ and δ is an infallible

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