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Resolution Theminimu md etectable angle an optical system can detect. Becauseof di ffraction, there is a limit
tothe minimum angle, resolution. Thelarger the aperture, the better the resolution.
RightAscensi on: (RA) Theangul ar distance of a celestial object measured in hours, minutes, and seconds along the
CelestialEquator eastward from the Vernal Equinox.
S-
SiderealRate Thisis the angular speed at which the Earth is rotating. Telescopetracking motors drive the
telescope at this rate. Therate is 15 arc seconds per second or 15 degree s per hour.
T-
Terminator Theboundaryline between the light and dark portion of the moonor a planet.
U-
Universe Thetotality of astronomical things, events, relations and energies capable of being described
objectively.
V-
VariableStar A star whoseb rightnessvaries over time due to either inherent properties of the star or something
eclipsingor obscuring the brightness of the star.
W-
WaningMoon Theperiod of the moon's cycle between full andnew, when its illuminated portion is decreasing.
WaxingMoon Theperiod of the moon's cycle between new andfull, when its illuminated portion is increasing.
Z-
Zenith Thepoint on the Celestial Sphere directly above the observer.
Zodiac Thezodiac is the portionof the Celestial Sphere that lies within 8 degrees 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 degrees in
width, comprise the zodiac. These signs coincided with the zodiacal constellations about 2 ,000 years
ago.Becau se of the Precession of the Earth's axis, the Vernal Equinox has moved westward by
about30 degrees since that time; the signs have moved with it and thus no longercoincide with the
constellations.