Table of Contents
Advertisement
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 surface
detail on Mars, you will need a high-power eyepiece and very
steady air!
E. 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.
F. 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. Our eyes are not sensitive enough to see color in
deep-sky objects except in a few of the brightest ones. 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: Star Hopping
Star hopping, as it is called by astronomers, is perhaps the
simplest way to hunt down deep-sky 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 closer 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 star hopping may seem challenging 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 constel-
lations in the night sky, you will need to get a planisphere to
identify them.
14
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 visu-
al magnitude of 9 or lower. Many beginners start with the
Messier objects, which represent some of the best and bright-
est 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
another suitably bright star near the bright star currently cen-
tered in the finder. Keep in mind that the field of view of the
finder scope is 6°, so you should choose another star that is
no more that 6° 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 13). 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
Figure 13. Star hopping 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.
Advertisement
Table of Contents
