The Elements of Astronomy: A Text-book for Use in High Schools and Academies; with AuranographyGinn, 1889 - 430 стор. |
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The Elements of Astronomy: A Text-Book for Use in High Schools and Academies ... Charles Augustus Young Попередній перегляд недоступний - 2018 |
Загальні терміни та фрази
altitude angle astronomical astronomical units atmosphere axis azimuth bright Cassiopeia celestial equator celestial sphere centre circle comet constellation corona declination density determined disc Dist distance Double Stars earth earth's orbit earth's surface east eclipse equal equatorial eye-piece feet force globe gravity heat heavenly bodies heliometer horizon inches instrument Jupiter known latitude length light longitude lunar lunar eclipse magnitude Mags Mars mass mean measured meridian meridian circle meteoric method miles minutes moon moon's motion moving naked eye nearly nebula node object object-glass observations orbit parallax perihelion period perturbations photosphere planet pole Pole-star position radius right ascension ring rotation satellites seen shadow sidereal sidereal period Sirius solar spectroscope spectrum star's Sun Spots sun's surface synodic synodic period telescope tide tion transit Uranus usually velocity Venus vernal equinox visible zenith
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Сторінка 18 - ... is the great circle in which the plane of the earth's equator cuts the celestial sphere. It is often called the
Сторінка 23 - See year. ecliptic. The apparent annual path of the sun among the stars; the intersection of the plane of the earth's orbit with the celestial sphere. The ecliptic is a great circle of the celestial sphere inclined at an angle of about 23°27
Сторінка 174 - The squares of the periods of the planets are proportional to the cubes of their mean distances from the sun ; that is, ti2 : k2 ,• ,• ai3 ,• (h3This is the so-called harmonic law.
Сторінка 30 - An exact definition of the astronomical latitude of a place has already been given (Art. 40). It is (1) the angle between the direction of gravity and the plane of the equator, which is the same as the altitude of the pole. (2) It may also be defined as the declination of the zenith, as is clear from Fig. 10, where PB, the altitude of the pole, equals QZ (since PQ and ZB are each 90°), and QZ by the very definition of declination (Art. 31) is . . , the declination of the zen ith.
Сторінка 186 - ... computed. The parallax of an object may be found, if two observers under the same meridian, but at a very great distance from one another, observe its zenith distance on the same day at the time of its passage over the meridian.
Сторінка 215 - On it place a globe, two feet in diameter; this will represent the Sun; Mercury will be represented by a grain of mustard seed, on the circumference of a circle 164 feet in diameter for its orbit; Venus a pea, on a circle 284 feet in diameter; the Earth also a pea, on a circle of 430 feet; Mars a rather large pin's head, on a circle of 654 feet; Juno, Ceres, Vesta, and Pallas, grains of sand, in orbits of from 1000 to 1200 feet; Jupiter a moderate-sized orange...
Сторінка 383 - If we use the naked eye, we cannot see the image distinctly from a distance much less than a foot, but if we use a magnifying lens of, say, one inch focus, we can view it from a distance of only an inch, and it will look correspondingly larger. Without stopping to prove the principle, we may say that the magnifying power is simply equal to the quotient obtained by dividing the focal length of the object-glass by that of the eye-lens; or, as a formula M = - ; that is, — in the figure.
Сторінка 100 - The libration in latitude is due to the fact that the moon's equator does not coincide with the plane of its orbit, but makes with it an angle of about 62°.
Сторінка 149 - Calory,"' which is the quantity of heat required to raise the temperature of one kilogram of water 1° C.; and as the result of the best observations thus far made, it appears that the solar constant is between 25 and 30 of these "calories...