Orion SPACEPROBE 130ST EQ - Manual (Page 13)

Every telescope has a useful limit of magnification of about
2x per millimeter of aperture. Which comes to about 260x
for the SpaceProbe 130ST. Claims of higher power by some
telescope manufacturers are a misleading advertising gimmick
and should be dismissed. Keep in mind that at higher powers,
an image will always be dimmer and less sharp (this is a fun-
damental law of optics). The steadiness of the air (the “seeing”)
can also limit how much magnification an image can tolerate.
Whatever you choose to view, always start by inserting your
lowest-power (longest focal length) eyepiece to locate and
center the object. Low magnification yields a wide field of
view, which shows a larger area of sky in the eyepiece. This
makes acquiring and centering an object much easier. If you
try to find and center objects with high power (narrow field of
view), it’s like trying to find a needle in a haystack!
Once you’ve centered the object in the eyepiece, you can
switch to higher magnification (shorter focal length eye-
piece), if you wish. This is especially recommended for small
and bright objects, like planets and double stars. The Moon
also takes higher magnifications well.
Deep-sky objects, however, typically look better at medium
or low magnifications. This is because many of them are
quite faint, yet have some extent (apparent width). Deep-sky
objects will often disappear at higher magnifications, since
greater magnification inherently yields dimmer images. This
is not the case for all deep-sky objects, however. Many galax-
ies are quite small, yet are somewhat bright, so higher power
may show more detail.
The best rule of thumb with eyepiece selection is to start with
a low power, wide field, and then work your way up in magni-
fication. If the object looks better, try an even higher magnifi-
cation. If the object looks worse, then back off the magnifica-
tion a little by using a lower-power eyepiece.
Objects to Observe
Now that you are all set up and ready to go, one critical deci-
sion must be made: what to look at?
A. The Moon
With its rocky surface, the Moon is one of the easiest and
most interesting targets to view with your telescope. Lunar
craters, marias, and even mountain ranges can all be clearly
seen from a distance of 238,000 miles away! With its ever-
changing phases, you’ll get a new view of the Moon every
night. The best time to observe our one and only natural sat-
ellite is during a partial phase, that is, when the Moon is NOT
full. During partial phases, shadows are cast on the surface,
which reveal more detail, especially right along the border
between the dark and light portions of the disk (called the
“terminator”). A full Moon is too bright and devoid of surface
shadows to yield a pleasing view. Make sure to observe the
Moon when it is well above the horizon to get the sharpest
images.
Use an optional Moon filter to dim the Moon when it is very
bright. It simply threads onto the bottom of the eyepieces
(you must first remove the eyepiece from the focuser to
attach a filter). You’ll find that the Moon filter improves view-
ing comfort, and also helps to bring out subtle features on
the lunar surface.
B. The Sun
You can change your nighttime telescope into a daytime Sun
viewer by installing an optional full-aperture solar filter over
the front opening of the SpaceProbe 130ST EQ. The primary
attraction is sunspots, which change shape, appearance, and
location daily. Sunspots are directly related to magnetic activ-
ity in the Sun. Many observers like to make drawings of sun-
spots to monitor how the Sun is changing from day to day.
Important Note: Do not look at the Sun with any optical
instrument without a professionally made solar filter, or
permanent eye damage could result. Leave the cover-
caps on the finder scope, or, better yet, remove the find-
er scope from the telescope when solar viewing.
C. The Planets
The planets don’t stay put like the stars, so to find them
you should refer to Sky Calendar at our website, www.tele-
scope.com, or to charts published monthly in Astronomy,
Sky & Telescope, or other astronomy magazines. Venus,
Mars, Jupiter, and Saturn are the brightest objects in the
sky after the Sun and the Moon. Your SpaceProbe 130ST
EQ is capable of showing you these planets in some detail.
Other planets may be visible but will likely appear star-like.
Because planets are quite small in apparent size, optional
higher-power eyepieces are recommended and often need-
ed for detailed observations. Not all the planets are generally
visible at any one time.
JUPITER The largest planet, Jupiter, is a great subject for
observation. You can see the disk of the giant planet and
watch the ever-changing positions of its four largest moons—
Io, Callisto, Europa, and Ganymede. higher-power eyepieces
should bring out the cloud bands on the planet’s disk.
SATURN The ringed planet is a breathtaking sight when it is
well positioned. The tilt angle of the rings varies over a period
of many years; sometimes they are seen edge-on, while at
other times they are broadside and look like giant “ears” on
each side of Saturn’s disk. A steady atmosphere (good see-
ing) is necessary for a good view. You will probably see a
bright “star” close by, which is Saturn’s brightest moon, Titan.
VENUS At its brightest, Venus is the most luminous object in
the sky, excluding the Sun and the Moon. It is so bright that
sometimes it is visible to the naked eye during full daylight!
Ironically, Venus appears as a thin crescent, not a full disk,
when at its peak brightness. Because it is so close to the
Sun, it never wanders too far from the morning or evening
horizon. No surface markings can be seen on Venus, which
is always shrouded in dense clouds.
MARS The Red Planet makes its closest approach to Earth
every two years. During close approaches you’ll see a red
disk, and may be able to see the polar ice cap. To see sur-
face detail on Mars, you will need a high-power eyepiece and
very steady air!
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