Meade EXT90 Instruction Manual page 47

Planets change positions in the sky as they orbit
around the Sun. To locate the planets on a given day or
month, consult a monthly astronomy magazine, such
as Sky and Telescope or Astronomy. You can also
consult ETX90 for information about planets. Scroll to
the "Object: Solar System" menu and scroll through
the lists of planets. When a planet you are interested
in displays, press "ENTER". Use the Scroll keys to
display information about the planet, such as the
planet's coordinates, and the rise and set times (Tip:
enter a date in the Date menu and you can determine
if a planet) will be visible during the night of the entered
date by checking its rise and set times). Listed below
are the best planets for viewing through the ETX90.
Mars is about half the diameter of Earth, and appears
through the telescope as a tiny reddish-orange disk.
It may be possible to see a hint of white at one of the
planet's Polar ice caps. Approximately every two years,
when Mars is closest to Earth in its orbit, additional
detail and coloring on the planet's surface may
be visible.
orbit Jupiter so that the number of moons visible on
any given night changes as they circle around the giant
planet.
Saturn is nine times the diameter of Earth and appears
as a small, round disk with rings extending out from
either side. In 1610, Galileo, the first person to observe
Saturn through a telescope, did not understand that
what he was seeing were rings. Instead, he believed
that Saturn had "ears." Saturn's rings are composed of
billions of ice particles ranging in size from a speck of
dust to the size of a house. The major division in Saturn's
rings, called the Cassini Division, is occasionally visible
Jupiter is the largest planet
in our solar system and is 11
times the diameter of Earth.
The planet appears as a disk
with dark lines stretching
across the surface. These
lines are cloud bands in
the atmosphere. Four of
Jupiter's 16 moons (Io,
Europa, Ganymede, and
Callisto) can be seen as
"star-like" points of light
when using even the lowest
magnification. These moons
Stars are large gaseous objects that are self-
illuminated by nuclear fusion in their core. Because
of their vast distances from our solar system, all stars
appear as pinpoints of light, irrespective of the size of
the telescope used.
Nebulae are vast interstellar clouds of gas and dust
where stars are formed. Most impressive of these is
the Great Nebula in Orion (M42), a diffuse nebula that
appears as a faint wispy gray cloud. M42 is 1600 light
years from Earth.
Open Clusters are loose groupings of young stars,
all recently formed from the same diffuse nebula.
The Pleiades is an open cluster 410 light years away.
Through the ETX90, numerous stars are visible.
Constellations are large, imaginary patterns of stars
believed by ancient civilizations to be the celestial
equivalent of objects, animals, people, or gods. These
patterns are too large to be seen through a telescope.
To learn the constellations, start with an easy grouping
of stars, such as the Big Dipper in Ursa Major. Then,
use a star chart to explore across the sky.
Galaxies are large assemblies of stars, nebulae,
and star clusters that are bound by gravity. The most
common shape is spiral (such as our own Milky Way),
but galaxies can also be elliptical, or even irregular
blobs. The Andromeda Galaxy (M31) is the closest
spiral-type galaxy to our own. This galaxy appears
fuzzy and cigar-shaped. It is 2.2 million light years
away in the constellation Andromeda, located between
the large "W" of Cassiopeia and the great square of
Pegasus.
through the ETX90. Titan,
the largest of Saturn's 18
moons can also be seen
as a bright, star-like object
near the planet.
Deep-Sky Objects
Star charts can be used
to locate constellations,
individual stars and deep-
sky objects.
Examples of various
deep-sky objects are
given below: