ELELMEN TS OF ASTRONOMY1873 |
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Common terms and phrases
angle aphelion apparent motion apparent movements appear astronomers atmosphere attraction axis Boötes bright called celestial equator celestial pole celestial sphere centre changes circle clock color comet constellations density Describe determined diameter direction disk distance Earth Earth's orbit Earth's rotation Earth's surface equal equatorial eye-piece fact globe gravity heat heavenly body heavens hemisphere Hence horizon inclined inferior planet Jupiter latitude length lens light longitude lunar magnitude Mars mass mean Sun Mercury meridian meteors miles Moon Moon's move naked eye nearest nearly nebula Neptune night node northern object-glass observed parallax path perihelion period photosphere polar position prism rays refraction represented revolution revolve round right ascension ring round the Sun satellites Saturn seen shadow sidereal solar day solstice southern spectrum spots stars Sun's superior planet suppose tance telescope tion Uranus Ursa vapor variable stars velocity Venus vernal equinox visible zenith zenith-distance
Popular passages
Page 20 - A sphere is a solid bounded by a curved surface, every point of which is equally distant from a point within called the center.
Page 20 - Every circumference of a. circle, whether the circle be large or small, is supposed to be divided into 360 equal parts called degrees. Each degree is divided into 60 equal parts called minutes, and each minute into 60 equal parts called seconds.
Page 153 - A man placed on one of them would spring with ease 60 feet high, and sustain no greater shock in his descent than he does on the earth from leaping a yard.
Page 132 - Almost directly preceding, or at 270°, appeared a bluntly triangular pink body, suspended, as it were, in the corona. This was separated from the moon's edge when first seen, and the separation increased as the moon advanced. It had the appearance of a large conical protuberance, whose base was hidden by some intervening soft and ill-defined substance, like the upper part of a conical mountain, the lower portion of which was obscured by clouds or thick mist. I think the apex of this object must...
Page 137 - Mars, in several respects, bears a striking resemblance to our earth. Its rotation round its axis is accomplished in nearly the same time as the earth, namely, in 24 hours and 40 minutes. The inclination of its axis to the plane of its orbit is 28 degrees and 42 minutes, that of the earth being 23 degrees 28 minutes.
Page 130 - Moon's shadow sweeps across the surface of the Earth, and is even seen in the air; the rapidity of its motion and its intenseness produce a feeling that something material is rushing over the Earth at a speed perfectly frightful.
Page 147 - Ansce^ or handles, given to the rings in certain positions of the planet. It was next supposed to consist of three bodies, the largest in the middle.
Page 237 - Bearing in mind that what an astronomer wants is a good clear image of the object observed, we shall at once recognise that magnifying power depends upon the perfection of the image thrown by the object-glass and upon the illuminating power.
Page 54 - ... proof that the object consists of true stars. These luminous points, in some nebulae at least, must be regarded as themselves gaseous bodies, denser portions, probably, of the great nebulous mass, since they exhibit a constitution which is identical with the fainter and outlying parts which have not been resolved. These...
Page 76 - Jupiter a moderate-sized orange, in a circle nearly half a mile across; Saturn a small orange, on a circle of four-fifths of a mile; Uranus a full-sized cherry, or small plum, upon the circumference of a circle more than a mile and a half, and Neptune a good-sized plum on a circle about two miles and a half in diameter.