Eclipse
an interception or obscuraother heavenly body by the intervention of another and non-luminous heavenly body or by its shadow. An eclipse of a star may be divided into three classes: solar, or planet is called occultation. Eclipses lunar, and planetary.
Solar Eclipses. An eclipse of the sun is an occultation of part of the face of the moon between the earth and the sun; the sun, occasioned by an interposition of thus all eclipses of the sun happen at the time of the new moon.
The dark or central part of the moon's shadow, where the sun's rays are wholly interis called the umbra, and the light part, where only a part of them are intercepted, is called the penumbra; and it is evident that if a spectator be situated on that part of the earth where the umbra falls, there will be a total eclipse of the sun at that place; in the penumbra there will be no eclipse. As the earth is not always at the same distance from the the earth is so far from the moon that moon, if an eclipse should happen when the rays of light proceeding from the upper and lower limbs of the sun across each other before they reach the earth, a spectator situated on the earth in a direct line between the centers of the sun and moon, would see a ring of light around the dark body of the moon; such an eclipse is called annular; when this happens there can be no total eclipse anywhere, because the moon's umbra does not reach the earth. People situated in the penumbra will perceive a partial eclipse; an eclipse can never be annular longer than 12 minutes 24 seconds, nor total longer than 7 minutes 58 seconds; nor can the duration of any eclipse of the sun exceed two hours. An eclipse of the sun begins on the W. side of his disk and ends on the E.; and an eclipse of the moon begins on the eastern 30-Vol. III-Cyc ECLIPSE side of her disk and ends on the western.
The average number of eclipses in a year is four, two of the sun and two of the moon; and as the sun and moon are as long below the horizon of any particular place as they are above it, the average number of visible eclipses in a year is two, one of the sun and one of the moon.
Total eclipses of the sun offer brief but intensely interesting phenomena for the astronomer's study. The nature of the sun's corona is as yet undetermined, and the aid of the spectroscope and of photography has not been sufficiently applied to the settling of the various problems presented. There were solar eclipses May 18, 1901, Aug. 30, 1905, Aug. 21, 1914, June 8, 1918, May 29, 1919.
Lunar Eclipses. An eclipse of the moon is an obscuration of the light of the ÉCOLE POLYTECHNIQUE formerly used to determine longitudes since they are the same viewed from all parts of the earth. The dates of a number of important events of antiquity have been approximately determined by calculations concerning eclipses recorded at or near the time. Eclipses have been calculated up to the year 2161.
ÉCOLE DES BEAUX ARTS (ā-kol da bo zär) (School of Fine Arts), the French Government school in Paris, founded by Mazarin in 1648, and provided with an extensive staff of teachers. The competitions for the grands prix de Rome take place at this school. artists between the age of 15 and 25, whether pupils of this school or not, may compete, after passing two preliminary examinations. The successful compet- All SUN PLANE OF THE ECLIPTIC PLANE OF THE ECLIPTIC ↓ A SUN B EARTH MOONS ORBIT MOONS PENUMBRA PENUMBRA EARTH A. Eclipse of the moon ECLIPSE moon occasioned by an interposition of the earth between the sun and the moon; consequently, all eclipses of the moon happen at full moon; for it is only when the moon is on that side of the earth which is turned away from the sun, and directly opposite, that it can come within the earth's shadow. Further, the moon must at that time be at the same time in the same plane as the earth's shadow; that is, the plane of the ecliptic in which the latter always moves. But as the moon's orbit makes an angle of more than 5° with the plane of the ecliptic, it frequently happens that, though the moon is in opposition, it does not come within the shadow of the earth.
Planetary Eclipses. The eclipse of a satellite takes place when the shadow of the primary obscures it. Jupiter offers the most favorable field for observation of this phenomenon. Such eclipses were B. Eclipse of the sun itors receive an annual allowance from the state for three or four years, two of The which must be passed at Rome. school has about 2,000 students enrolled, and about 50 instructors.
ÉCOLE POLYTECHNIQUE (pol-itek-nēk') (Polytechnic School), a school in Paris established with the purpose of giving instruction in matters connected with the various branches of the public service, such as mines, roads and bridges, engineering, the army and the navy, government manufactures, etc. It was founded in 1794, and is under the direction of the Minister of War. Candidates are admitted only by competitive examination, and have to pay for their board (about $200 a year). The pupils who pass satisfactory examinations at the end of their course are admitted to that branch of public service which they select.
ECONOMIC ASSOCIATION ICAN, a society founded in 1885 by