Meade DS-2000 Series Bedienerhandbuch PDF herunterladen (Seite 44)

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

You can also consult Autostar 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(s) will be visible during the night of the entered date by checking

its r

ise and set times). Listed below are the best planets for viewing through the DS-2000

Series.

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

surface 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 moons (Io, Europa, Ganymede, and Callisto) can be seen

as “star-like” points of light when using even the lowest magnification (

Fig. 38). 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. 39). 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. Titan, the largest of Saturn’s 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. 40).

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 e

en irregular b

lobs

The Andromeda Galaxy (M31) is the closest spiral-type galaxy to

our o

wn.

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 great square of

egasus

Fig. 39: Saturn has

the most extensive

ring structure in our

Solar System.

Fig. 40: The

Pleiades is one of

the most beautiful

open clusters.

Fig. 38: Jupiter and

its four largest

moons. The moons

can be observed in

a different position

every night.

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