Astronomy for Schools and CollegesH. Holt, 1879 - 512 oldal |
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altitude amount angle angular appear astronomers atmosphere attraction axis called celestial sphere centre circle clock comet constellation declination described determine diameter direction disk diurnal diurnal motion earth earth's surface east eclipse equal equator fixed stars force gravitation heat heavenly bodies heavens Hence HERSCHEL horizon hour angle inferior conjunction interval Jupiter kilometres known latitude latter length light longitude lunar magnitude Mars mass mean distance measured Mercury meridian meteoroids meteors Milky minutes months moon moon's motion move naked eye nearly nebula Neptune node number of stars object observer orbit parallax pass perihelion period photosphere planet planetary pole position proper motion radius ratio rays refraction revolution revolve right ascension ring rotation satellites Saturn seen shadow sidereal solar system spectrum spots sun's supposed telescope theory tion transit Uranus velocity Venus vernal equinox visible zenith
Népszerű szakaszok
134. oldal - To every action there is always opposed an equal reaction: or, the mutual actions of two bodies upon each other are always equal, and directed to contrary parts.
134. oldal - The change of motion is proportional to the motive force impressed; and is made in the direction of the right line in which that force is impressed.
170. oldal - THE MOON. The mean distance of the moon from the earth is about 60 radii of the latter, while, as we have just seen, the length 'EV of the earth's shadow is 217 radii of the earth. Hence when the moon passes through the shadow she does so at a point less than three tenths of the way from E to V. The radius of the shadow here will be...
134. oldal - Every body continues in its state of rest or of uniform motion in a straight line, unless it is compelled to change that state by forces impressed upon it.
125. oldal - The square of the period of a planet is proportional to the cube of its mean distance from the Sun.
177. oldal - If the orbit of the moon around the earth were in or near the plane of the ecliptic there would be an eclipse of the sun at every new moon, and an eclipse of the moon at every full moon. But...
459. oldal - If this matter is self-luminous, it seems more fit to produce a star by its condensation than to depend on the star for its existence...
400. oldal - B' is zero, the mean distance will become infinite. Hence, ih this case the body will fly off to an infinite distance from the sun and never return. Much less will it return if the velocity is still greater. Such a velocity will make the value of a algebraically negative and will correspond to the hyperbola. If we take one kilometre per second as the unit of velocity, and the mean distance of the earth from the sun as the unit of distance, the value of...
339. oldal - Mars to see an object the size of a large animal on the satellite. This short distance and rapid revolution make the inner satellite of Mars one of the most interesting bodies with which we are acquainted. It performs a revolution in its orbit in less than half the time that Mars revolves on its axis. In consequence, to the inhabitants of Mars, it would seem to rise in the west and set in the east. It will be remembered that the...
v. oldal - To facilitate its use by students of different grades, the subject-matter is divided into two classes, distinguished by the size of the type. The portions in large type form a complete course for the use of those who desire only such a general knowledge of the subject as can be acquired without the application of advanced mathematics. The portions in small type comprise additions for the use of those students who either...