Celestron CPC Deluxe 1100 HD Computerized Telescope - Manual (Page 38)

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R –
Reflector A telescope in which the light is collected by means
of a mirror .
Resolution The minimum detectable angle an optical system
can detect. Because of diffraction, there is a limit
to the minimum angle, resolution . The larger the
aperture, the better the resolution .
Right The angular distance of a celestial
Ascension: (RA) object measured in hours, minutes and
seconds along the Celestial Equator eastward
from the Vernal Equinox .
S –
Schmidt Rated the most important advance in optics .
Telescope 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 (1879-1935).
Sidereal Rate This is the angular speed at which the Earth is
rotating . Telescope tracking motors drive the
telescope at this rate . The rate is 15 arc
seconds per second or 15 degrees per hour .
T –
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 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 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 . Because of the
Precession of the Earth’s axis, the Vernal Equinox
has moved westward by about 30 degrees since
that time; the signs have moved with it and thus no
longer coincide with the constellations .