7
The Planets
The planets don’t stay put like the stars, so you’ll have to refer
to charts published monthly in
Astronomy, Sky & Telescope,
or other astronomy magazines to locate them. Venus, Mars,
Jupiter, and Saturn are the brightest objects in the sky after
the Sun and the Moon. Not all four of these planets are nor-
mally visible at any one time.
JUPITER The largest planet, Jupiter, is a great subject to
observe. 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. If atmospheric conditions
are good, you may be able to resolve thin 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 may see a tiny, bright
“star” close by; that’s 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 You probably won’t be able to see much surface detail
on the Red Planet, but if conditions are particularly good you
may notice some light and dark areas, and possibly even a
white polar ice cap.
Stars
Stars will appear like twinkling points of light in the telescope.
Even powerful telescopes cannot magnify stars to appear as
more than points of light! You can, however, enjoy the differ-
ent colors of the stars and locate many pretty double and
multiple stars. The famous “Double-Double” in the constella-
tion Lyra and the gorgeous two-color double star Albireo in
Cygnus are favorites. Defocusing the image of a star slightly
can help bring out its color.
Deep-Sky Objects
Under dark skies, you can observe a wealth of fascinating
deep-sky objects, including gaseous nebulas, open and glob-
ular star clusters, and some of the brighter galaxies. Most
deep-sky objects are very faint, so it is important that you find
an observing site well away from light pollution. Take plenty of
time to let your eyes adjust to the darkness. Don’t expect
these subjects to appear like the photographs you see in
books and magazines; most will look like dim gray smudges.
(Our eyes are not sensitive enough to see color in such faint
objects.) But as you become more experienced and your
observing skills get sharper, you will be able to ferret out more
and more subtle details.
Note: Remember that the higher the magnification you
use, the dimmer the image will appear. So stick with low
power when observing deep-sky objects because they’re
already very faint.
Consult a star atlas or observing guide for information on find-
ing and identifying deep-sky objects. Some good sources to
start with are the
Edmund Mag 6 Star Atlas, Turn Left at
Orion, and The Universe From Your Backyard.
6. Terrestrial Viewing
Your Observer 70mm may also be used for long-distance view-
ing over land. For this application we recommend substitution of
an Orion 45° Correct-Image Diagonal (#8790) for the 90° star
diagonal that comes standard with the telescope. The correct-
image diagonal will yield an upright, non-reversed image and
also provides a more comfortable viewing angle, since the tele-
scope will be aimed more horizontally for terrestrial subjects.
For terrestrial viewing, it’s best to stick with low powers of 50x
or less. At higher power the image loses sharpness and clar-
ity because of unsteady air. That’s because when the scope
is pointed near the horizon it’s peering through the thickest
and most turbulent part of the Earth’s atmosphere.
Note: Remember to aim well clear of the Sun, unless the
front of the telescope is fitted with a professionally made
solar filter and the finder scope is covered with foil or
some other completely opaque material.
7. Care and Maintenance
If you give your telescope reasonable care, it will last a lifetime.
Store it in a clean, dry, dust-free place, safe from rapid changes
in temperature and humidity. Do not store the telescope out-
doors, although storage in a garage or shed is OK. Small
components like eyepieces and other accessories should be
kept in a protective box or storage case. Keep the objective
lens cap on the front of the telescope when it is not in use.
Your Observer 70 requires very little mechanical mainte-
nance. The optical tube is aluminum and has a smooth
painted finish that is fairly scratch-resistant. If a scratch does
appear on the tube, it will not harm the telescope. If you wish,
you may apply some auto touch-up paint to the scratch.
Smudges on the tube can be wiped off with a soft cloth and a
household cleaner such as Windex or Formula 409.
Cleaning the Optics
A small amount of dust or a few specks on the glass objective
(main) lens will not affect the performance of the telescope. If dust
builds up, however, simply blow it off with a blower bulb, or lightly
brush it off with a soft camel-hair brush. Avoid touching optical
surfaces with your fingers, as skin oil may etch optical coatings.
To remove fingerprints or smudges from a lens, use photo-
graphic-type lens cleaning fluid and lint-free optical lens
cleaning tissue. Don’t use household cleaners or eyeglass-
type cleaning cloth or wipes, as they often contain undesirable
additives like silicone, which don’t work well on precision
