16
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 surface
detail on Mars, you will need a high power eyepiece and very
steady air!
D. The Stars
Stars will appear like twinkling points of light. Even powerful
telescopes cannot magnify stars to appear as more than a
point of light! You can, however, enjoy the different colors of
the stars and locate many pretty double and multiple stars.
The famous “Double-Double” in the constellation Lyra and the
gorgeous two-color double star Albireo in Cygnus are
favorites. Defocusing a star slightly can help bring out its color.
E. 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 a variety of different types of 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. Do not
expect these subjects to appear like the photographs you see
in books and magazines; most will look like dim gray
smudges. But as you become more experienced and your
observing skills get sharper, you will be able to ferret out more
and more subtle details and structure.
How to Find Deep-sky Objects: Starhopping
Starhopping, as it is called by astronomers, is perhaps the sim-
plest way to hunt down objects to view in the night sky. It entails
first pointing the telescope at a star close to the object you wish
to observe, and then progressing to other stars closer and clos-
er to the object until it is in the field of view of the eyepiece. It is
a very intuitive technique that has been employed for hundreds
of years by professional and amateur astronomers alike. Keep
in mind, as with any new task, that starhopping may seem chal-
lenging at first, but will become easier over time and with
practice.
To starhop, only a minimal amount of additional equipment is
necessary. A star chart or atlas that shows stars to at least
magnitude 5 is required. Select one that shows the positions of
many deep-sky objects, so you will have a lot of options to
choose from. If you do not know the positions of the constella-
tions in the night sky, you will need to get a planisphere to
identify them.
Start by choosing bright objects to view. The brightness of an
object is measured by its visual magnitude; the brighter an
object, the lower its magnitude. Choose an object with a visual
magnitude of 9 or lower. Many beginners start with the Messier
objects, which represent some of the best and brightest deep-
sky objects, first catalogued about 200 years ago by the French
astronomer Charles Messier.
Determine in which constellation the object lies. Now, find the
constellation in the sky. If you do not recognize the constella-
tions on sight, consult a planisphere. The planisphere gives an
all-sky view and shows which constellations are visible on a
given night at a given time.
Now, look at your star chart and find the brightest star in the
constellation that is near the object you are trying to find. Using
the finder scope, point the telescope at this star and center it on
the crosshairs. Next, look again at the star chart and find anoth-
er suitably bright star near the bright star currently centered in
the finder. Keep in mind that the field of view of the finder scope
is approximately 7°, so you should choose another star that is
no more that 7° from the first star, if possible. Move the tele-
scope slightly, until the telescope is centered on the new star.
Continue using stars as guideposts in this way until you are at
the approximate position of the object you are trying to find
(Figure 21). Look in the telescope’s eyepiece, and the object
should be somewhere within the field of view. If it’s not, sweep
the telescope carefully around the immediate vicinity until the
object is found.
If you have trouble finding the object, start the starhop again
from the brightest star near the object you wish to view. This
time, be sure the stars indicated on the star chart are in fact the
stars you are centering in the eyepiece. Remember, the finder
scope (and main telescope eyepiece, for that matter) gives an
inverted image, so you must keep this in mind when starhop-
ping from star to star.
Figure 21.
Starhopping is a good way to locate hard-to-find
objects. Refer to a star chart to map a route to the object that uses
bright stars as guideposts. Center the first star you’ve chosen in the
finder scope and telescope eyepiece (1). Now move the scope
carefully in the direction of the next bright star (2), until it is
centered. Repeat (3 and 4). The last hop (5) should place the
desired object in the eyepiece.
