Meade ETX Astro Telescope/ETX Spotting Scope Instruction Manual download pdf (Page 42)

Planets

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

Astronom

Listed below are the best planets for viewing through the ETX-80AT.

Venus is about nine-tenths the diameter of Earth. As Venus orbits the Sun, observers can see

it go through phases (crescent, half

, and full) much like those of the Moon. The disk of Venus

appears white as Sunlight is reflected off the thick cloud cover that completely obscures any

surf

ace detail.

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.

Jupiter is the largest planet in our solar system and is 11 times the diameter of Earth.The plan-

et 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 (

Fig. 35). These

moons 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 (Fig. 36). 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 through the ETX-80AT. 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:

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 (

Fig. 37). Through the ETX-80AT,

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 ellip-

tical, 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 betw

een the large

“W”

of Cassiopeia and the g

reat square

of P

egasus

Fig. 36: Saturn has

the most extensive

ring structure in our

Solar System.

Fig. 327 The

Pleiades is one of

the most beautiful

open clusters.

Fig. 35: Jupiter and

its four largest

moons. The moons

can be observed in

a different position

very night.

Polaris

Little Dipper

Big Dipper

Cassiopeia

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Meade ETX Astro Telescope/ETX Spotting Scope Instruction Manual Page 42

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