Appendix B - Glossary Of Terms - Celestron XLT series Instruction Manual

A p p e n d i x B -
A p p e n d i x B -
A-
Abs olute magnitude
Air y d isk
Alt-Azimuth Mounting
Alti tude
Ape rture
App arent Magnitude
Arc minute
Arc second
Ast erism
Ast eroid
Ast rology
(AU)
Ast ronomical unit
Aur ora
Azi muth
B -
Binar y Stars
C -
Celestial Equator
Celestial pole
Celestial Sphere
Collimation
D -
(DEC)
Declination
E -
Ecliptic
Equatorial mount
F -
G l o s s a r y o f T
G l o s s a r y o f T
The apparent mag nitude th at a star wou
parsecs, or 32.6 li ght-years. The abs
would just be visible on Earth on a c
The apparent size f a star's disk produced even by a perfect optical system. Since the s o
be focused perfec tly, 84 per cen
a system of surrounding rings.
A telescope moun ting using two in
Altitude and Azim uth.
In astronomy, the altitud e of a celestial o
horizon.
the diameter of a telescope's primar
telescope
's light- gatheri ng power.
A measure of the relative brightness of a
Earth.
A unit of angu lar size equal to 1/
A unit of angular size equal to 1
unoffici al
A small grouping of star
A small, rocky bo dy that orbits a
T
he pseu doscientific belie f that the positions of stars and
affairs; a strology has nothing in common with astronomy
The dist ance between the Earth and the
150,0 00,000 km.
T
he emission of l ight wh en charged par
es in a p lanet'
molec ul s upper atmosphe
The an gular dista nce of an object eastwa
th e astronomical meridian (the vertical line passing through th
south points on the horizon)
be measured. .
(Double)
Binary stars are pairs of
around a comm on Center
is called a mul tip le system. It is beli
or multiple system s. Systems with i
are called visual b inaries or visual mu ples. The nearest "s
is actually our nearest example of a multiple star system, it consists of three stars
to our Sun and one dim, small, red star orbiting around one another.
The projection of the Earth's equator on to the celestial sphere. It divides the sky into two equal
hemispheres.
T e imaginary projection of Earth
h
An imaginary sphere surrounding the Earth, concentric with the Earth's center.
The act of putting a telescope'
The angular distance of a celestial body north or south of the celestial equator. It may be said to
correspond to latitude on the surface of the Earth.
The projection of the Earth's orbit on to the celestial sphere. It may also be defined as "the apparent
yearly path of the Sun against the stars".
A telescope mounting in which the instrument is set upon an axis which is parallel to the axis of the
Earth; the angle of the axis must be equal to the observer's latitude.
e r m s
e r m s
ld have if it were obser
olut e magnitude of the
lear m oonless night awa
t of the ligh t will concen
depe ndent rotation axis allowing movement
bject is it s Angular Di
y len s or mirror; the la
star or other celestial
60 of a degree.
/3,600 o f a degree (or 1/60 of an arcminute).
s in the night sky.
star.
Sun. I t is equal to 149,
ticles f rom the solar w
re.
rds alo ng the horizon,
and the ver tical line containing th
st ars that, because of th
of Ma s s. If a group of three o
eved that approximate
ndiv idual components
lti
's rotational axis north or south pole onto the celestial sphere.
s optics into perfect alignment.
50
ved from a standard di
Sun is 4.8. at a distanc e o
y fro m surface light .
trate into a single disk , and 1
of the
stance above or below
rger the aperture, the g reate
objec t as perceived by
planets exert an influence o
.
597,90 0 km., usually rounded off to
s
ind slam into and exc
measu red from due no
cente r
e of the sky and the north and
e celesti al body whose position is to
e ir m utual gravitation al att
r mo re stars revolve a r ound
ly 50 percent of all sta rs be
that can be seen separa tely
tar " to our solar system , A
,
two very similar
stance of 10
f 10 parsecs, it
tar can neve r
6 per cent into
instrument in
the c elestial
r the
an obse rver on
n human
s
ite at oms and
rth, be tween
on, orbit
racti
one another, it
long to binary
a
by telescope
lpha Centauri,