Objects In Space - Meade ETX-90EC Instruction Manual

Important Note: For almost all astronomical observing requirements approximate settings of the telescope's
latitude and polar axis are acceptable! Do not allow undue attention to precise polar alignment of the telescope to
interfere with your basic enjoyment of the instrument.
In those unusual cases where more precise polar alignment is desirable, refer to
OBSERVING

OBJECTS IN SPACE

Listed below are some of the many astronomical objects that can be seen with
the ETX-90EC.
The Moon
The Moon is, on average, a distance of 239,000 miles (380,000km) from Earth
and is best observed during its crescent or half phase, when sunlight strikes its
surface at an angle, casting shadows and adding a sense of depth to the view
(Fig. 17). No shadows are seen during a full Moon, causing the overly bright
Moon to appear flat and rather uninteresting through the telescope. Using the
ETX-90EC, brilliant detail can be observed on the Moon, including hundreds of lunar craters and maria, described
below.
Craters are round meteor impact sites covering most of the Moon's surface.
With no atmosphere on the Moon, no weather conditions exist, so the only
erosive force is meteor strikes. Under these conditions, lunar craters can last for
millions of years.
Maria (plural for mare) are smooth, dark areas scattered across the lunar
surface. These dark areas are large ancient impact basins that were filled with
lava from the interior of the Moon by the depth and force of a meteor or comet
impact.
12 Apollo astronauts left their bootprints on the Moon in the late 1960's and early 1970's. However, no telescope
on Earth is able to see these footprints or any other artifacts. In fact, the smallest lunar features that may be seen
with the largest telescope on Earth are about one-half mile across.
NOTE: Except during its early or late crescent phases, the Moon can be an exceptionally bright object to view
through the telescope. To reduce the brightness and glare, use the #905 Variable Polarizing Filter (see
ACCESSORIES).
Planets
Planets change positions in the sky as they orbit around the Sun. To locate the planets on a given day or month,
Fig. 16: Locating Polaris.
APPENDIX C.
WARNING! Never use the
Meade ETX-90EC Astro
Telescope to look at the Sun!
Looking at or near the Sun
will
cause instant andirreversible damage to
your eye. Eye damage is often painless,
so there is no warning to the observer
that damage has occurred until it is too
late. Do not point the telescope or its
viewfinder at or near the Sun. Do not
look through the telescope or its
viewfinder as it is moving. Children
should always have adult supervision
while observing.
Fig. 17: Photo of the Moon shows rich detail
afforded by shadows.
OPTIONAL