orizon; celestial, any great circle passing from one pole
to the other.
METEORS, 119; swarm of, meeting the earth, 118; explosion of, 120;
systems of, 123; relation of, to comets, 124.
MICROMETER, any instrument for the accurate measurement of very
small distances or angles.
MIND, origin of force, 252; continuous relation of, to the
universe, 252.
MILKY WAY, 210, 215.
MIRA, the Wonderful, 221.
MOON, the, 151; greatest and least distance from the earth, 10;
telescopic appearance of, 155.
MURAL CIRCLE, 61.
NADIR, the point in the celestial sphere directly beneath our feet,
opposite to zenith.
NEBULAE, 217.
NEBULAR HYPOTHESIS, not atheistic, 182; stated, 182; confirmatory
facts, 183; objections to, 185.
NEPTUNE, elements of, 175.
NODE, the point in which an orbit intersects the ecliptic, or
other plane of reference; ascending, descending, line of, 107.
OCCULTATION, the hiding of a star, planet, or satellite by the
interposition of a nearer body of greater angular magnitude.
OPPOSITION. A superior planet is in opposition when the sun,
earth, and the planet are in a line, the earth being in the middle.
ORBIT, the path of a planet, comet, or meteor around the sun, or of
a satellite around a primary; inclination of, 106; earth's, seen
from the stars, 70.
OUTLINE FOR STUDENTS, 276.
PARALLAX, the difference of direction of a heavenly body as seen
from two points, as the centre of the earth and some point of its
surface, 69.
PARALLELS, imaginary circles on the earth or in the heavens parallel
to the equator, having the poles for their centre.
PERIGEE, nearest the earth; said of a point in an orbit.
PERIHELION, the point of an orbit nearest the sun.
PERIODIC TIME, time of a planet's, comet's, or satellite's
revolution.
PERSONAL EQUATION, 65.
PERTURBATION, the effect of the attractions of the planets or other
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bodies upon each other, disturbing their regular motion; of Saturn
and Jupiter, 11; of asteroids, 13; of Uranus and Neptune, 176.
PHASES, the portions of the illuminated half of the moon or
interior planet, as seen from the earth, called crescent, full, and
gibbous.
PHOTOSPHERE of the sun, 89.
PLANET (_a wanderer_), as seen from space, 99; speed of, 101;
size of, 102; movements retrograde and direct, 112.
POINTERS, the, 197.
POLE, NORTH, movement of, 198.
POLES, the extremities of an imaginary line on which a celestial
body rotates.
QUADRANT, the fourth par