AstronomyAstronomy, which etymologically means "law of the stars", (from Greek: αστρονομία = άστρον + νόμος) is a science involving the observation and explanation of events occurring outside Earth and its atmosphere. It studies the origins, evolution, physical and chemical properties of objects that can be observed in the sky (and are outside the earth), as well as the processes involving them. \n \n \n , photographed by the crew of Apollo 11 as they circled the Moon in 1969. Located near the center of the far side of Earth's Moon, its diameter is about 93 kilometers (58 miles).]]
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 that 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; astronomers embrace the scientific method, while astrologers do not.
Ways of obtaining information\nIn astronomy, information is mainly received from the detection and analysis of electromagnetic radiation,\nphotons, but information is also carried by cosmic rays, neutrinos, meteors, 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:
 . This image shows several blue, loop-shaped objects that are multiple images of the same galaxy. They have been duplicated by the gravitational lens effect of the cluster of yellow galaxies near the photograph's center. The lens is produced by the cluster's gravitational field that bends light to magnify and distort the image of a more distant object.]]
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\nwater 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, so observations\ncan be carried out only from balloons or space observatories.
Short history\nIn 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. Astronomy was mostly stagnant in medieval Europe, but flourished meanwhile in the Arab world. 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 was 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 tables and performed a reformation of the calendar that 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. Galileo added the innovation of using telescopes to enhance his observations. Kepler was the first to devise a system that described correctly the details of the motion of the planets with the Sun at the center. However, Kepler did not succeed in formulating a theory 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. In addition, that scientist developed the reflecting telescope to further enhance observations. Stars were found to be faraway 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. . The ejection of gas, from the dying star at the center, has symmetrical patterns unlike the chaotic patterns expected from an ordinary explosion.]]
Timelines in astronomy\n* Timeline of artificial satellites and space probes\n* Timeline of astronomical maps, catalogs, and surveys\n* Timeline of black hole physics\n* Timeline of cosmic microwave background astronomy\n* Timeline of cosmology\n* Timeline of galaxies, clusters of galaxies, and large scale structure\n* Timeline of natural satellites\n* Timeline of other background radiation fields\n* Timeline of solar astronomy\n* Timeline of solar system astronomy\n* Timeline of stellar astronomy\n* Timeline of telescopes, observatories, and observing technology\n* Timeline of the Big Bang\n* Timeline of the interstellar medium and intergalactic medium\n* Timeline of the Universe\n* Timeline of white dwarfs, neutron stars, and supernovaeSee also\n* List of astronomical topics\n* Astronomers and Astrophysicists\n* Space science\n* Astronomical naming conventions\n* Astronomical symbols\n* Astronomical object\n* Astronomical cycles\n* International Astronomical Union\n* American Astronomical Society\n* Royal Astronomical Society\n* European Southern ObservatoryAstronomy tools\n* Telescope\n* Computers\n* Calculator\n* Observatory\n* Space observatoryExternal links\nOrganizations\n*American Association of Variable Star Observers\n*American Astronomical Society\n*Astronomical Society of the Pacific\n*Cassini Imaging Laboratory - Stunning images of the planets taken by the Cassini exploratory spacecraft\n*Czech Astronomical Society\n*Durham Region Astronomical Association\n*Hawaiian Astronomical Society\n*Herzberg Institute of Astrophysics\n*National Optical Astronomy Observatories\n*North York Astronomical Association\n*Open Encyclopedia Project - Astronomy Section.\n*Royal Astronomical Society of Canada\n*Royal Astronomical Society (UK)\n*Royal Astronomical Society of New Zealand\n*Saint Louis Astronomical Society\n*Society for Popular Astronomy (UK)\n*International Astronomy Youth Camp (IAYC)References: Formulas and Constants\n* Astronomy Formulas \n* Astronomical Constants Index\n* Zombeck's Handbook of Space Astronomy and AstrophysicsExternal links\n* Astronomy sites for educators \n* Los Alamos Astrophysics e-Print Database\n* Astronomy Picture of the Day\n* Bruce Medalists (annual astronomical award since 1898)\n*Islamic and Arab Astronomy \nCategory:Natural sciences\nCategory:Astronomy \n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\nnds:Astronomie\n\n\n\n\n\nsimple:Astronomy\n\n\n\n\n\n\n\n\n\nzh-cn:天文学\nzh-tw:天文學\n |
||||
"The difference between fiction and reality? Fiction has to make sense." - Tom Clancy |
on 