APSIS n.
One of the two points of an orbit, as of a planet or satellite, which are at the greatest and least distance from the central body, corresponding to the aphelion and perihelion of a planet, or to the apogee and perigee of the moon. The more distant is called the higher apsis; the other, the lower apsis; and the line jo…
IMMERSION n.
hind another, as in the occultation of a star, or into its shadow, as in the eclipse of a satellite; -- opposed to emersion. Immersion lens, a microscopic objective of short focal distance designed to work with a drop of liquid, as oil, between the front lens and the slide, so that this lens is practically immersed.…
MOON n. 2 definitions
The celestial orb which revolves round the earth; the satellite of the earth; a secondary planet, whose light, borrowed from the sun, is reflected to the earth, and serves to dispel the darkness of night. The diameter of the moon is 2,160 miles, its mean distance from the earth is 240,000 miles, and its mass is one eig…
NEBULAR a.
of matter, from which subsequently, by the same laws, were produced the several planets, satellites, and other bodies of the system. The phrase may indicate any hypothesis according to which the stars or the bodies of the solar system have been evolved from a widely diffused nebulous form of matter.…
REVOLUTION n.
The motion of any body, as a planet or satellite, in a curved line or orbit, until it returns to the same point again, or to a point relatively the same; -- designated as the annual, anomalistic, nodical, sidereal, or tropical revolution, according as the point of return or completion has a fixed relation to the year,…