| resolution. |
Right Ascension: (RA) | the angular distance of a celestial object measured in hours, minutes, and seconds along |
| the Celestial Equator eastward from the Vernal Equinox. |
S - |
|
Schmidt Telescope | Rated the most important advance in optics in 200 years, the Schmidt telescope combines |
| the best features of the refractor and reflector for photographic purposes. It was invented in |
| 1930 by Bernhard Voldemar Schmidt |
Sidereal Rate | This is the angular speed at which the Earth is rotating. Telescope tracking motors drive |
T - | the telescope at this rate. The rate is 15 arc seconds per second or 15 degrees per hour. |
| |
Terminator | The boundary line between the light and dark portion of the moon or a planet. |
U - |
|
Universe | The totality of astronomical things, events, relations and energies capable of being |
V - | described objectively. |
| |
Variable Star | A star whose brightness varies over time due to either inherent properties of the star or |
W - | something eclipsing or obscuring the brightness of the star. |
| |
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 |
Z - | increasing. |
| |
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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