Bresser National Geographic 90-11100 Mode D'emploi page 19

Possible observation targets
The following section details several interesting and easy-to-find celestial objects you may want to
observe through your telescope. The pictures (Page 9) show what the objects will look like through
your telescope's eyepiece.
The moon
The moon is Earth's only natural satellite.
Diameter: 3,476 km / Distance: 384,400 km from Earth (average)
The moon has been known to humans since prehistoric times. It is the second brightest object in
the sky, after the sun. Because the moon circles the Earth once per month, the angle between the
Earth, the moon and the sun is constantly changing; one sees this change in the phases of the
moon. The time between two consecutive new moon phases is about 29.5 days (709 hours).
Constellation Orion: The Orion Nebula (M 42)
h
Right Ascension: 05
Distance: 1,344 light years from Earth
Though it is more than 1,344 light years from Earth, the Orion Nebula (M 42) is the brightest diffuse
nebula in the sky. It is visible even with the naked eye and a worthwhile object for telescopes of all
types and sizes. The nebula consists of a gigantic cloud of hydrogen gas with a diameter of hun-
dreds of light years.
Constellation Lyra: The Ring Nebula (M 57)
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Right Ascension: 18 53
Distance: 2,412 light years from Earth
The famous Ring Nebula (M57) in the Lyra constellation is often viewed as the prototype of a plan-
etary nebula. It is one of the magnificent features of the Northern Hemisphere's summer sky. Recent
studies have shown that it is probably comprised of a ring (torus) of brightly shining material that
surrounds the central star (only visible with larger telescopes), and not a gas structure in the form
of a sphere or an ellipse. If you were to look at the Ring Nebula from the side, it would look like the
Dumbbell Nebula (M 27). When viewed from Earth, we are looking directly at the pole of the nebula.
Constellation Vulpecula (Little Fox):
The Dumbbell Nebula (M 27)
h
Right Ascension: 19
Distance: 1,360 light years from Earth
The Dumbbell Nebula (M 27) was the first planetary nebula ever discovered. On 12 July 1764,
Charles Messier discovered this new and fascinating class of objects. We see this object almost
directly from its equatorial plane. If we could see the Dumbbell Nebula from one of its poles, we
would probably see the shape of a ring, something very similar to what we know as the Ring Nebula
(M 57). In reasonably good weather, we can see this object well, even with low magnification.
m
35 (hours : minutes) / Declination: -05° 22' (Degrees : minutes)
m
(hours : minutes) / Declination: +33° 02' (Degrees : minutes)
m
59 (hours : minutes) / Declination: +22° 43' (Degrees : minutes)
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