Celestron NexStar 8 Instruction Manual page 45

U -
Universe The totality of astronomical things, events, relations and energies capable of being described
objectively.
V -
Variable Star A star whose brightness varies over time due to either inherent properties of the star or something
eclipsing or obscuring the brightness of the star.
W -
Waning Moon The period of the moon's cycle between full and new, when its illuminated portion is decreasing.
Waxing Moon The period of the moon's cycle between new and full, when its illuminated portion is increasing.
Z -
Zenith The point on the Celestial Sphere directly above the observer.
Zodiac The zodiac is the portion of the Celestial Sphere that lies within 8 deg on either side of the Ecliptic.
The apparent paths of the Sun, the Moon, and the planets, with the exception of some portions of the
path of Pluto, lie within this band. Twelve divisions, or signs, each 30 deg in width, comprise the
zodiac. These signs coincided with the zodiacal constellations about 2,000 years ago. Because of the
Precession of the Earth's axis, the Vernal Equinox has moved westward by about 30 deg since that
time; the signs have moved with it and thus no longer coincide with the constellations.
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