තාරකා විද්‍යාව
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- This article is about the branch of science. For information about the magazine, see Astronomy (magazine).
තාරකා විද්‍යාව (ඉංග්‍රීසි: Astronomy / ඇස්ට්‍රොනොමි) (ග්‍රීක: αστρονομία = άστρον + νόμος, astronomia / ඇස්ට්‍රොනොමියා = astron + nomos, සරලව ගත් කල, "තාරකා නීතිය") යනු තාරකා, ග්‍රහලෝක, ධූමකේතු (comets), ඌෂාලෝකය (aurora), චක්‍රාවාට (galaxies) සහ අන්තරීක්ෂ පසුබිම් විකිරණය (cosmic background radiation) යනාදී පෘථිවි වායුගෝලයෙන් පරිභාහිර සංසිද්දීන් සහ අභ්‍යවකශ වස්තූන් (celestial objects) පිලිබඳ විද්‍යාවයි. මෙහි ප්‍රධාන කාර්යයන් වන්නේ විශ්වයේ සම්භවය සහ විකාශණය, විශ්ව වස්තූන්ගේ භෞතික සහ රසායනික ගුණයන්ගේ පරිනාමය සහ ඒවායේ චලනයන් යනාදිය ගැන හැදෑරීමයි. මෙහි එන විද්‍යාත්මක නිරීක්ෂණයන් වැදගත් වන්නේ තාරකා විද්‍යාවට පමණක් නොවේ, ඒවා සාමාන්‍ය සාපේක්ෂතා වාදය වැනි භෞතික විද්‍යාත්මක මතවාදයන් සනාථ කරගැනීමට අවශ්‍ය වැදගත් තොරතුරු ද සපයයි.
තාරකා විද්‍යාව යනු විද්‍යාත්මක ක්‍රමය රැගත් ලෝකයේ පැරණිම විද්‍යාවන්ගෙන් එකකි. එය පෞරාණික ග්‍රීක යුගය දක්වා දිවයන අතර දියුණු නිරීක්ෂණ ක්‍රම ඊටත් වඩා ඈත අතීතය කරා දිවයයි. ඓතිහාසික වශයෙන් ගත්කල තාරකා විද්‍යාවේ වැදගත් සොයාගැනීම් රැසකට දායක වී ඇත්තේ ආධුනික තාරකා විද්‍යාඥයන්ය. එසේම අදට ද තාරකා විද්‍යාව යනු ආධුනිකයන්ගේ දායකත්වය නොමසුරුව ලැබිය හැකි "විද්‍යාවන්" අතලොස්සෙන් එකකි. ඒ නව සොයාගැනීම් වලින් සහ කෙටි කාල පරාසයන් තුල සිදුවන සංසිද්දීන් නිරීක්ෂණය කිරිමෙන්ය.
නූතන තාරකා විද්‍යාව සහ ජ්‍යෝතීෂ්‍යය යන දෙකෙහිම පදනම සැලකිය යුතු තරමකට සමානය. ග්‍රහ වස්තූන්හි අහසේ පිහිටීම මත යම් පුද්ගලයකුගේ හෝ පොදුවේ මනුෂ්‍ය වර්ගයාගේ දෛවය ප්‍රකාශ කිරීමට ජ්‍යෝතීෂ්‍යය උත්සාහ කරයි. එහෙත් තාරකා විද්‍යාවේ කටයුතු වලදී "විද්‍යාත්මක ක්‍රමය" යන්න භාවිතා වන අතර ජ්‍යෝතිෂ්‍යයේදී එසේ නොවේ. එමනිසා මේ දෙක සම්පූර්ණයෙන්ම වෙනස් ක්ෂේත්‍ර දෙකක් ලෙස සැලකිය යුතුය.
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[edit] Divisions
In Babylon, and ancient Greece, astronomy consisted largely of astrometry, measuring positions of stars and planets in the sky. Later, with the work of astronomers Kepler and Newton, whose work led to the development of celestial mechanics, the mathematical prediction of the motions of celestial bodies interacting gravitationally became the focus of astronomy. This was applied to solar system objects in particular. Motions and positions of objects are now more easily determined, and modern astronomy is more concerned with observing and understanding the actual physical nature of celestial objects.
Since the twentieth century, the field of professional astronomy has split into observational astronomy and theoretical astrophysics. Observational astronomy is concerned mostly with acquiring data, which involves building and maintaining instruments and processing the results; this branch is at times referred to as "astrometry" or simply as "astronomy". Theoretical astrophysics is concerned mainly with ascertaining the observational implications of different models, and involves working with computer or analytic models.
The fields of study can also be categorized in other ways. Categorization by the region of space under study (for example, Galactic astronomy, Planetary Sciences); by subject, such as star formation or cosmology; or by the method used for obtaining information.
[edit] By subject or problem addressed
- Astrometry: the study of the position of the objects in the sky and their changes of the position in the sky. Defines the system of coordinates used and the kinematics of objects in our galaxy.
- Astrophysics: the study of physics of the universe, including the physical properties (luminosity, density, temperature, chemical composition) of astronomical objects.
- Cosmology: the study of the origin of the universe and its evolution. The study of cosmology is theoretical astrophysics at its largest scale.
- Galaxy formation and evolution: the study of the formation of the galaxies, and their evolution.
- Galactic astronomy: the study of the structure and components of our galaxy and of other galaxies.
- Extragalactic astronomy: the study of objects (mainly galaxies) outside our galaxy.
- Stellar astronomy: the study of the stars.
- Stellar evolution: the study of the evolution of stars from their formation to their end as a stellar remnant.
- Star formation: the 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.
- Planetary Sciences: the study of the planets of the Solar System.
- Astrobiology: the study of the advent and evolution of biological systems in the Universe.
Other disciplines that may be considered part of astronomy:
- Archaeoastronomy
- Astrochemistry
- Astrosociobiology
See the list of astronomical topics for a more exhaustive list of astronomy related pages.
[edit] Ways of obtaining information
- Main article: Observational astronomy.
In astronomy, information is mainly received from the detection and analysis of light and other forms of electromagnetic radiation. Other cosmic rays are also observed, and several experiments are designed to detect gravitational waves in the near future.
A traditional division of astronomy is given by the region of the electromagnetic spectrum observed:
- Optical astronomy is the part of astronomy that uses optical components (mirrors, lenses, CCD detectors and photographic films) to observe light from near infrared to near ultraviolet wavelengths. Visible light astronomy (using wavelengths that can be detected with the eyes, about 400 - 700 nm) falls in the middle of this range. The most common tool is the telescope, with electronic imagers and spectrographs.
- Infrared astronomy deals with the detection and analysis of infrared radiation (wavelengths longer than red light). The most common tool is the telescope but using a detector which is sensitive to the infrared. Space telescopes are also used to avoid atmospheric thermal emission, atmospheric opacity, and the effects of astronomical seeing at infrared and other wavelengths.
- Radio astronomy detects radiation of millimetre to dekametre wavelength. The radio telescope receivers are similar to those used in radio broadcast transmission but much more sensitive.
- High-energy astronomy includes X-ray astronomy, gamma ray astronomy, and extreme UV (ultraviolet) astronomy, as well as studies of neutrinos and cosmic rays.
Optical and radio astronomy can be performed with ground-based observatories, because the Earth's atmosphere is transparent at the wavelengths being detected. Infrared radiation is heavily absorbed by atmospheric water vapour, so infrared observatories have to be located in high, dry places or in space.
The atmosphere is opaque at the wavelengths of X-ray astronomy, gamma-ray astronomy, UV astronomy and (except for a few wavelength "windows") far infrared astronomy, so observations must be carried out mostly from balloons or space observatories. Powerful gamma rays can, however be detected by the large air showers they produce, and the study of cosmic rays can also be regarded as a branch of astronomy.
[edit] History of astronomy
- Main article: History of astronomy.
In early times, astronomy only comprised the observation and predictions of the motions of the naked-eye objects. Aristotle said that the Earth was the centre of the Universe and everything rotated around it in orbits that were perfect circles. Aristotle had to be right because people thought that Earth had to be in the centre with everything rotating around it because the wind would not scatter leaves, and birds would only fly in one direction. For a long time, people thought that Aristotle was right, but it is probable that Aristotle accidentally did more to hinder our knowledge than help it.
The Hindu vedic text, 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 described the earth as spinning on its axis and considered the motions of the planets with respect to the sun.
East Asia's first astronomical observatory was developed in Silla, one of Three Kingdoms of Korea, under the reign of Queen Seondeok of Silla. It was termed Cheomsongdae, and is one of the oldest surviving scientific installations on Earth. It means star-gazing tower in Korean.
Although classical astronomy was one of the seven key subjects taught at medieval universities in Europe, observational astronomy was mostly stagnant in medieval Europe until XIII century, when lived astronomers and astrologers as Johannes de Sacrobosco, in England, and Guido Bonatti from Forlì, in Italy.
Tycho Brahe's work is very famous, in the 16th Century. However, observational astronomy flourished in the Iranian world and other parts of Islamic realm. The late 9th century Persian astronomer 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, Persia (now Iran), by the Persian astronomer al-Khujandi, who observed a series of meridian transits of the Sun, which allowed him to calculate the obliquity of the ecliptic. Also in Persia, Omar Khayyám performed a reformation of the calendar that was more accurate than the Julian and came close to the Gregorian. Abraham Zacuto was responsible in the 15th century for the adaptations of astronomical theory for the practical needs of Portuguese caravel expeditions.
In Europe 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 centre. 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. Newton also developed the reflecting telescope.
Stars were found to be faraway objects. With the advent of spectroscopy it was proved that they were similar to Earth's own sun, but with a wide range of temperatures, masses, and sizes. The existence of Earth's 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. Modern astronomy has also discovered many exotic objects such as quasars, pulsars, blazars and radio galaxies, and has used these observations to develop physical theories which describe some of these objects in terms of equally exotic objects such as black holes and neutron stars. Physical 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.
[edit] Timelines in astronomy
- Artificial satellites and space probes
- Astronomical maps, catalogues, and surveys
- Big Bang
- Black hole physics
- Cosmic microwave background astronomy
- Cosmology
- Galaxies, clusters of galaxies, and large scale structure
- Interstellar medium and intergalactic medium
- Natural satellites
- Other background radiation fields
- Solar astronomy
- Solar system astronomy
- Stellar astronomy
- Telescopes, observatories, and observing technology
- White dwarfs, neutron stars, and supernovae
[edit] තවද බලන්න
Dictionary definitions from Wiktionary
Textbooks from Wikibooks
Quotations from Wikiquote
Source texts from Wikisource
Images and media from Commons
News stories from Wikinews
- List of astronomical topics
- Astronomers and Astrophysicists
- Astronomical symbols
- Astronomical cycles
- Astronomical naming conventions
- Astronomical object
- Astronomical observatories
- Astronomy organisations
- Celestial navigation
- Space exploration
- Space science
- Astronomical objects named after people
[edit] Astronomy tools
- Binoculars
- Telescope
- Computers
- Calculator
- Observatory
- Space observatory
- Maksutov telescope
[edit] External links
- AbsoluteAstronomy.com
- NASA
- Southern Hemisphere Astronomy
- Astronomy Picture of the Day
- New Scientist Space
- Sky & Telescope
- American Astronomical Society
- Planet Surveyor
- Utah Skies Astronomy Information by and for Amateur Astronomers
- ebook History of Astronomy, George Forbes (1849-1936
- The Amazing Sky
- Space and Astronautics News
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තාරකා විද්‍යාවේ ප්‍රධාන උප ක්‍ෂෙත්‍ර |
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| Astrophysics | Cosmology | Galactic astronomy | Extragalactic astronomy | Galaxy formation and evolution | Planetary science | Stellar astronomy | Stellar evolution | තාරකා සම්භවය |
| General subfields within the Natural sciences |
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