National Geographic NG90EQ - Manual (Page 13)

13
CARE AND CLEANING OF OPTICS
Optical components of a telescope get dirty over time. Dirt or dust on a lens should be
removed with the utmost care. A considerable amount of dirt or dust would have to
accumulate on the optical surface before your view would be compromised.
1) Keeping dust caps on during storage and transport will reduce dust collection.
2) Condensation may collect on the optical surfaces when the telescope is not in use.
Remove the dust caps and allow the moisture to evaporate naturally. Point the
telescope downward to minimize the accumulation of airborne dust.
3) Once all moisture has evaporated, replace the dust caps.
4) Filtered, compressed air may be used to remove surface dust from lenses and
mirrors. Remove the dust cap and the dew shield. Once removed, point the can away
from the lens and gently expel some air and any condensation or dust that has
accumulated on the discharge tube. Spray the lens or mirror with short bursts of air to
carefully remove the dust particles. DO NOT HOLD THE TRIGGER OF THE
COMPRESSED AIR CAN FOR EXTENDED PERIODS BECAUSE PROPELLANT
FROM THE CAN MIGHT ESCAPE AND DAMAGE THE OPTICAL SURFACE.
If, after several attempts, you cannot remove the particles, take the telescope to an
optical professional for cleaning.
If you keep the dust caps on your telescope when it is not in use and avoid handling the
lenses or mirrors, only minimal optical maintenance of your telescope should be
required. Extensive cleaning is usually only necessary every few years.
WHAT TO LOOK FOR IN THE NIGHT SKY
There is a whole universe of objects you could view at night, so where do you start?
We recommend starting with the most prominent objects first.
The moon
The moon is the easiest target to find at night. When the moon is in full position, it
bathes the night with a silvery light that washes the sky of all but the brightest objects.
The best time to view the moon is not when it is full, but rather when it is less than half
full. The dividing line between dark and light on the moon, called the terminator, shows
the best detail in the craters and mountains.
The planets
The planets, our solar system companions, range in size and substance from moon-size
rocky bodies to giant gas balls, which could hold Earth 1,000 times over. To find the
planets, you will need information about their times of visibility. An astronomy magazine
will give you the locations of the planets as they change position from month to month.
The Internet is also an excellent source of information, offering star charts, maps, and
more!