Astronomia

shenim: duke u perkthyer

Astronomi, qe nga etimologjia do te thote "ligji i yjeve",(ne Greqisht): &#940;&#963;&#964;&#961;&#959;, + &#957;&#972;&#956;&#959;&#962;) eshte nje shkenc qe perfshin observimin dhe spjegimin e ngjarjeve  qe ndodhin jashte Tokes dhe atmosferes. Ajo studjon origjinen, evolimin, vetite fizike dhe kimike te te gjith objekteve qe mund te verehen ne qiell (qe jan jasht Tokes), se bashku me te gjith proceset ne te cilat ato perfshihen. Me ndryshimin e koherave kane ndryshuar dhe nenfushat e saj te studimit. Gjate nje pjese te mire te shekullit XX, astronomia ishte menduar te ndahet ne astrometri, mekanika qiellore dhe astrofizike. Nga te treja, astrofizika, eshte ndier me shume pasi ne shum Universitete perfshihet ne departamente kerkimi dhe zhvillimi.

 image:moon.crater.arp.300pix.jpg '' Lunar astronomy: the far side of Earth's Moon. The large impact basin pictured is Crater 308. It spans about 30 kilometers (19 miles) and was photographed by the crew of Apollo 11 as they circled the Moon in 1969'' [[media:moon.crater.arp.750pix.jpg|Larger version ]]

Astronomy is one of the few sciences where amateurs still play an active role, especially in the discovery and monitoring of transient phenomena. Astronomy is not to be confused with astrology, a pseudoscience which attempts to predict a person's destiny by tracking the paths of astronomical objects. Although the two fields share a common origin, they are quite different; astronomy embraces the scientific method, while astrology, with no basis in science, does not.

Divisions of astronomy
Given its huge scope, astronomy is divided into different branches. A first main distinction is between theoretical and observational astronomy. Observers use a variety of means to obtain data about different phenomena, data that is then used by theorists to create and constrain theories and models, to explain observations and to predict new ones; observer and theorist are not necessarily different persons, and rather than two perfectly delimited fields, there is a continuum of scientists that put more or less emphasis in observation or theory.

Fields of study are also categorized in another two ways: by subject, usually according to the region of space (e.g. Galactic astronomy) or problems addressed (such as star formation or cosmology); or by the way used for obtaining information (essentially, what region of the electromagnetic spectrum is used). While the first division is applicable to both observers and theorist, the second one applies only to observers (imperfectly), as theorists try to use all the information available, in all wavelength, and observers often observe in more than one region of the spectrum.

By subject or problem addressed
 '' Planetary astronomy, or Planetary Sciences: a Martian dust devil. Photographed by the NASA Global Surveyor in Mars orbit, the long dark streak is formed by the movement of a swirling column of Martian atmosphere (with similarities to a terrestrial tornado). The dust devil (the black spot) is climbing the crater wall. Dust devils occur when the atmosphere is heated by a warm surface and begins to spin as it rises. The streaks in the right hand half of the picture are sand dunes on the crater floor.'' [[media:dust.devil.mars.arp.750pix.jpg|Larger version ]]


 * Astrometry: Measures positions of objects in the sky and their changes.Necessary to define the system of coordinates used and the kinematics of object in our galaxy.
 * Cosmology: Study of the universe as a whole and its evolution.
 * Galactic astronomy: It used to be the study of the structure and components of our galaxy. Now includes study of other galaxies that can be observed in detail.
 * Extragalactic astronomy: Study of objects (mainly galaxies) outside our galaxy.
 * Galaxy formation and evolution: Study of the formation of the galaxies, and its evolution to the observed present state.
 * Planetary Sciences: The study of the planets of the solar system is (in recent times), sometimes considered a different discipline; also called Planetology
 * Stellar astronomy: Study of stars, in general.
 * Stellar evolution: Study of the evolution of stars from its formation to its end as a stellar remnant.
 * Star formation: Study of the condition and processes that led to the formation of stars in the interior of gas clouds, and the process of formation itself.

Also, there are other disciplines that may be considered part of astronomy, or are interdisciplinary sciences related to astronomy:


 * Archeoastronomy
 * Astrobiology
 * Astrochemistry
 * Planetary sciences
 * Cosmology

See list of astronomical topics for a more exhaustive list of astronomy-related pages.

By ways of obtaining information
In astronomy, the main way of obtaining information is through the detection and analysis of electromagnetic radiation, photons, but information is also carried by cosmic rays, neutrinos, and, in the near future, gravitational waves (see LIGO and LISA).

A traditional division of astronomy is given by the region of the electromagnetic spectrum observed:


 * Optical astronomy refers to the techniques used to detect and analyze light in and slightly around the wavelengths than can be detected with the eyes (about 400 - 800 nm). The most common tool is the telescope, with electronic imagers and spectrographs.
 * Infrared astronomy deals with the detection of infrared radiation (wavelengths longer than red light). The most common tool is the telescope but with the instrument optimized for infrared.  Space telescopes are also used to eliminate noise (electromagnetic interference) from the atmosphere.
 * Radio astronomy uses completely different instruments to detect radiation of wavelengths of mm to cm. The receivers are similar to those used in radio broadcast transmission (which uses those wavelengths of radiation). See also Radio telescopes.
 * High-energy astronomy

 '' Extragalactic astronomy: gravitational lensing. This Hubble Space Telescope image shows several blue, loop-shaped objects that actually are multiple images of the same galaxy. They have been duplicated by the gravitational lens effect of the cluster of yellow, elliptical and spiral galaxies near the photograph's center. The gravitational lens is produced by the cluster's tremendous gravitational field that bends light to magnify, brighten and distort the image of a more distant object.'' Click on the picture for more information and a larger version.

Optical and radio astronomy can be performed with ground-based observatories, because the atmosphere is transparent at those wavelengths. Infrared light is heavily absorbed by water vapor, so infrared observatories have to be located in high, dry places or in space.

The atmosphere is opaque at the wavelengths used by X-ray astronomy, gamma-ray astronomy, UV astronomy and, except for a few wavelength "windows", Far infrared astronomy, and so observations can be carried out only from balloons or space observatories.

Short history
In the early part of its history, astronomy involved only the observation and predictions of the motions of the objects in the sky that could be seen with the naked eye. The Rigveda refers to the 27 constellations associated with the motions of the sun and also the 12 zodiacal divisions of the sky. The ancient Greeks made important contributions to astronomy, among them the definition of the magnitude system. The Bible contains a number of statements on the position of the earth in the universe and the nature of the stars and planets, most of which are poetic rather than literal; see Biblical cosmology. In 500 AD, Aryabhata presented a mathematical system that took the earth to spin on its axis and considered the motions of the planets with respect to the sun.

The study of astronomy almost stopped during the middle ages, except for the work of Arabic astronomers. The late 9th century Islamic astronomer al-Farghani (Abu'l-Abbas Ahmad ibn Muhammad ibn Kathir al-Farghani) wrote extensively on the motion of celestial bodies. His work were translated into latin in the 12th century. In the late 10th century, a huge observatory was built near Tehran, Iran, by the astronomer al-Khujandi who observed a series of meridian transits of the Sun, which allowed him to calculate the obliquity of the ecliptic. In Persia, Omar Khayyam (Ghiyath al-Din Abu'l-Fath Umar ibn Ibrahim al-Nisaburi al-Khayyami) compiled many astronomical tables and performed a reformation of the calendar which was more accurate than the Julian and came close to the Gregorian.

During the renaissance Copernicus proposed a heliocentric model of the Solar System. His work was defended, expanded upon, and corrected by Galileo Galilei and Johannes Kepler. Kepler was the first to devise a system which described correctly the details of the motion of the planets with the Sun at the center. However, Kepler did not understand the reasons behind the laws he wrote down. It was left to Newton's invention of celestial dynamics and his law of gravitation to finally explain the motions of the planets.

Stars were found to be far away objects. With the advent of spectroscopy it was proved that they were similar to our own sun, but with a wide range of temperatures, masses and sizes. The existence of our galaxy, the Milky Way, as a separate group of stars was only proven in the 20th century, along with the existence of "external" galaxies, and soon after, the expansion of the universe seen in the recession of most galaxies from us. Cosmology made huge advances during the 20th century, with the model of the big bang heavily supported by the evidence provided by astronomy and physics, such as the cosmic microwave background radiation, Hubble's Law and cosmological abundances of elements.

For a more detailed history of astronomy, see the history of astronomy.

 '' Stellar astronomy,Stellar evolution: The Ant planetary nebula. The ejection of gas, from the dying star at the center, has intriguing symmetrical patterns unlike the chaotic patterns expected from an ordinary explosion. Scientists using Hubble would like to understand how a spherical star can produce such prominent symmetries in the gas that it ejects.'' Click on the picture for more information and a larger version.

Astronomy Tools
http://www.asimpleclick.com/nasa_related.htm for additional info
 * Telescope
 * Computers


 * Calculator
 * Observatory
 * Space observatory

Organizations

 * American Association of Variable Star Observers
 * Durham Region Astronomical Association
 * National Optical Astronomy Observatories
 * North York Astronomical Association
 * Royal Astronomical Society of Canada
 * Royal Astronomical Society (UK)
 * Czech Astronomical Society
 * Herzberg Institute of Astrophysics
 * Saint Louis Astronomical Society