Skygazing

Skygazing is the act of observing the sky for pleasure or with an astronomical interest. Amateur astronomy observations are generally accomplished with the naked eye or with basic optical aids. Simple naked-eye observations of the sky can reveal a great deal about the basics of astronomy and a better understanding of the cosmos, while instruments, such as telescopes, are used to study deep space. Many different celestial objects can be viewed through skygazing during both the night and day.

Naked eye skygazing

Diurnal observation

The extreme brightness of the Sun saturates the sky during the day and prevents naked eye observation of less luminous objects, with the exception of the Moon and occasionally Venus.

Sunspots and solar eclipses can be viewed during the day using a telescope or binoculars fitted with approved safety filters. Extreme caution must be exercised to avoid permanent blindness. Some solar filters supplied with cheaper telescopes are not safe enough. Only filters clearly identified as complying with current safety standards should be used. [http://sunearth.gsfc.nasa.gov/eclipse/SEhelp/safety2.html] and [http://www.mreclipse.com/Special/filters.html]

Eclipses

The Newtonian

The Newtonian type is characterized by a long enough tube, a bit lower in its focal length and is composed of a parabolic main mirror to the substance bound to a flat alternative mirror close to the opening, oriented to 45°, that return the light outwards through the eyepiece. The observation makes itself therefore by the side of the tube that is open and will let dusts to enter and deposit themselves on the mirror. Its another inconvenience is that the temperature inside the tube is slightly higher than the temperature of the surrounding environment (at least in the beginning of the night), the hotter air, while escaping, will invoke the turbulences that will harm the quality of the picture.

Types of Catadioptrics

The Schmidt

The Schmidt is a design that uses all spherical surfaces, making it an instrument that is easy to manufacture. It employs a cassegrain design with a compound curve corrector plate at the front of the tube that "corrects" all the aberration a spherical system would have (and also gives the telescope the advantage of having a sealed tube). The secondary mirror in a Schmidt is mounted on the corrector plate.

The Maksutov

The Maksutov, is similar to the Schmidt except it uses a thick concave corrector plate and the secondary is usually a silvered spot on the backside of the corrector (a "spot-mak"). This design has the added advantage over a Schmidt in that it never needs alignment, all optical elements are fixed in alignment.

The big benefit of the reflecting telescope on the refracting telescope is its manufacturing cost, what permits to acquire for a reasonable amount an instrument of bigger diameter, lien of a big necessary brightness at the time of the observation of the distant and weakly luminous objects. Otherwise, the chromatic aberration doesn't exist with this type of instrument, but the alternative mirror overlooks goal in part, what is an inconvenience (loss of brightness of the order of 5 to 10%).A telescope, unlike a telescope, asks for an entretien : the primary mirror has a certain degree of freedom in the tube and can in some cases (a physical shock for example) to go out of order, requiring a realignment that one undertakes oneself thus. This same mirror being coated of a very fine coat of aluminium, deteriorates to the contact of air and has a life of 8 to 10 years. Specialist firms take care of the transaction.

Gallery

See also

*Astrophotography
*History of Astronomy
*Sky
*Telescope

External links

* [http://www.mreclipse.com/Special/SEprimer.html Solar Eclipses for Beginners]
* [http://www.nightskyinfo.com The Night Sky This Week]
* [http://www.astrofind.net/ AstroFind - Search Engine for Astronomy]
* [http://cleardarksky.com/csk Clear Sky Clocks] Weather forecasts for astronomers in North America