- 行业: Aerospace
- Number of terms: 16933
- Number of blossaries: 2
- Company Profile:
The Executive Branch agency of the United States government, responsible for the nation's civilian space program and aeronautics and aerospace research.
A celestial coordinate; it is the angular distance measured from the vernal equinox eastward along the celestial equator to the hour circle of a given star or other celestial body. It can be defined also as the arc of the celestial equator or the angle at the celestial pole between the hour circle of the vernal equinox and the hour circle of the body.
Industry:Astronomy
Backward (westward) motion of the planet among the stars, resulting from the fact that it is viewed from the moving earth. It is the motion that a planet has when its right ascension is decreasing. Each year, when Earth passes a superior planet, such as Mars, the planet appears to move backward for a short time. It is the same effect you see when two trains are running in the same direction on side by side tracks. The slower train appears to be moving backward.
Industry:Astronomy
Two bodies are in quadrature when their difference in celestial longitude is 90 degrees. This is the position of a superior planet when its elongation is 90 degrees, east or west, depending on the direction of the planet from the sun.
Industry:Astronomy
(1) a sun with respect to its planets, or a planet with respect to its satellites; (2) the brighter member of a double star system.
Industry:Astronomy
Anything that a flight vehicle carries beyond what is required for its operation during flight.
Industry:Astronomy
The hiding of one heavenly body by another, as when the moon passes between earth and a star, or when one of the moons of jupiter or saturn passes behind the planet.
Industry:Astronomy
The point on the celestial sphere that is diametrically opposite the zenith, so that the zenith, nadir and center of earth are in one straight line. It is always 90 degrees below the horizon.
Industry:Astronomy
The amount of matter in a body, which should not be confused with weight. The same object will have different weights in space and earth but the mass remains constant.
Industry:Astronomy
A "secondary rocket" intended to be used for descending to the surface of the moon or another planet while the major vehicle remains in an orbit around the destination body.
Industry:Astronomy
