COMPUTERIZED TELESCOPE
J
Jovian Planets
Any of the four gas giant planets that are at a greater distance form the Sun than the terrestrial planets.
K
Kuiper Belt
A region beyond the orbit of Neptune extending to about 1000 AU which is a source of many short pe-
riod comets.
L
Light-Year (ly)
A light-year is the distance light traverses in a vacuum in one year at the speed of 299,792 km/ sec. With
31,557,600 seconds in a year, the light-year equals a distance of 9.46 X 1 trillion km (5.87 X 1 trillion mi).
M
Magnitude
Magnitude is a measure of the brightness of a celestial body. The brightest stars are assigned magni-
tude 1 and those increasingly fainter from 2 down to magnitude 5. The faintest star that can be seen
without a telescope is about magnitude 6. Each magnitude step corresponds to a ratio of 2.5 in bright-
ness. Thus a star of magnitude 1 is 2.5 times brighter than a star of magnitude 2, and 100 times brighter
than a magnitude 5 star. The brightest star, Sirius, has an apparent magnitude of -1.6, the full Moon is
-12.7, and the Sun’s brightness, expressed on a magnitude scale, is -26.78. The zero point of the appar-
ent magnitude scale is arbitrary.
Meridian
A reference line in the sky that starts at the North celestial pole and ends at the South celestial pole and
passes through the zenith. If you are facing South, the meridian starts from your Southern horizon and
passes directly overhead to the North celestial pole.
Messier
A French astronomer in the late 1700’s who was primarily looking for comets. Comets are hazy diffuse
objects and so Messier cataloged objects that were not comets to help his search. This catalog became
the Messier Catalog, M1 through M110.
N
Nebula
Interstellar cloud of gas and dust. Also refers to any celestial object that has a cloudy appearance.
NORTH CELESTIAL POLE
The point in the Northern hemisphere around which all the stars appear to rotate. This is caused by the
fact that the Earth is rotating on an axis that passes through the North and South celestial poles. The
star Polaris lies less than a degree from this point and is therefore referred to as the “Pole Star”.
Nova
Although Latin for “new” it denotes a star that suddenly becomes explosively bright at the end
of its life cycle.
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Summary of Contents for NexStar 102 GT 102x1000 AZ
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