Astronomy is the science of celestial objects (e.g., stars, planets, comets, and galaxies) and phenomena that originate outside the Earth's atmosphere. It is concerned with the evolution, physics, chemistry, meteorology, and motion of celestial objects, as well as the formation and development of the universe. Astronomy is one of the oldest sciences. Astronomers of early civilizations performed methodical observations of the night sky, and astronomical artifacts have been found from much earlier periods. However, astronomy did not develop into a modern science until after the telescope was invented. The following outline is provided as an overview of and topical guide to astronomy.
Essence of astronomy
- Main article: Astronomy
Relation to astrophysics
The subjects of astronomy and astrophysics are very large and closely related, too overlaid and intertwined in almost all their branches for either to be considered subordinate to the other. Astronomy is the ancient subject, concerning the observations of bodies beyond the Earth (and also with timekeeping and calendar maintenance), together with the meaning of those observations and our understanding of the nature of those bodies. Astrophysics is much more recent. The basic understanding of the movement of celestial bodies, and its essential connection with earthly natural science, or physics, dates from the work of Galileo and Isaac Newton. The realization that the light of stars could be analyzed for clues about their physical nature, such as mass, size, temperature, composition, age, and evolution, began with the development of optical spectroscopy in the mid-19th century.
Thus uninterpreted observation may be considered as closest to pure astronomy, whereas physical modeling of the Universe, from comets and asteroids to the Sun, planets and stars, to cosmology and the Big Bang, becomes more nearly "pure astrophysics" (if indeed such a subject exists apart from speculation) the more it is concerned with laboratory and theoretical physics, and the more detached from observation. As astronomy has taught us a great deal about physics, so has physics (and its related fields, from mathematics to chemistry, and perhaps soon to include biology) proved essential to our understanding of astronomy.
Branches of astronomy
General astrophysics is the study of physics of the universe, including the physical properties (luminosity, density, temperature, chemical composition) of astronomical objects. Theoretical astrophysics seeks to explain and model the physical properties of the universe using the laws of physics and the physical sciences.
The subdisciplines of theoretical astrophysics
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| Astrobiology |
The advent and evolution of biological systems in the universe. |
| Compact objects |
Very dense matter in white dwarfs and neutron stars and their effects on environments including accretion. |
| Exoplanet studies |
The various planets outside of the Solar System |
| Physical cosmology |
The origin and evolution of the universe as a whole. The study of cosmology is theoretical astrophysics at its largest scale. |
| Galactic astronomy |
The structure and components of our galaxy and of other galaxies. |
| High energy astrophysics |
Phenomena occurring at high energies including active galactic nuclei, supernovae, gamma-ray bursts, quasars, and shocks. |
| Interstellar astrophysics |
The interstellar medium, intergalactic medium and dust. |
| Extragalactic astronomy |
Objects (mainly galaxies) outside our galaxy, including Galaxy formation and evolution. |
| Stellar astronomy |
Star formation, physical properties, main sequence life span, variability, stellar evolution and extinction. |
| Plasma astrophysics |
The properties of plasma in outer space. |
| Relativistic astrophysics |
The effects of special relativity and general relativity in astrophysical contexts including gravitational waves, gravitational lensing and black holes. |
Planetary Science is the study of the planets of the Solar System.
The subdisciplines of observational astronomy are generally made by the specifications of the detectors:
General techniques for astronomical research are also convenient ways of dividing the field:
- Photometry - the study of how bright celestial objects are when passed through different filters
- Spectroscopy - the study of the spectra of astronomical objects
- Astrometry - the study of the position of objects in the sky and their changes of position. Defines the system of coordinates used and the kinematics of objects in our galaxy.
Other disciplines that may be considered part of astronomy:
History of astronomy
- Main article: History of astronomy
Babylonian astronomy | Egyptian astronomy | Timeline of Chinese astronomy | Greek astronomy | Indian astronomy | Islamic astronomy | Science in Medieval Western Europe
General astronomy concepts
Basic phenomena
Atmosphere | Celestial pole | Eclipse | Ecliptic | Cosmic rays | Kepler's laws | Doppler effect | Nutation | Orbit | Perturbation | Precession | Proper motion | Redshift | Solar eclipse | Tides | Zodiac
Instruments, measurement and units
Radio telescope | Telescope | Calendar | Astronomical Unit | Celestial coordinates | Parsec | Precession | Celestial mechanics | Solar time | Sidereal time
Sun
Solar system
Stars and stellar objects
Binary star | Cepheid variable | Flare star | HR Diagram | Nova | Star formation |
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Constellations
Clusters and nebulae
Interstellar matter | Nebula | Crab Nebula | H I region | H II region | Orion nebula | Planetary nebula | Pleiades
Galaxies
Galaxy | Andromeda Galaxy | Magellanic Clouds | Quasar
Cosmology
Big Bang | Cosmic microwave background | Cosmos | Dark matter | Cosmic distance ladder | Hubble constant | Olber's paradox | Universe
Space exploration
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Organizations
AAVSO | AURA | IAU | ESA | JAXA | NASA | RAS | Webb Society
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| See also Timeline of first orbital launches by country. · 1 Preceded by the Soviet space program. |
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Books and publications
Almagest | Astronomia Nova | Astronomical Journal | Astrophysical Journal | BD Catalogue | De Revolutionibus | Henry Draper Catalogue | Isaac Asimov's Guide to Earth and Space | Messier Catalogue | New General Catalogue | Principia
Astronomers
Walter Baade | Friedrich Bessel | Tycho Brahe | Annie Jump Cannon | Alvan Clark | Nicholas Copernicus | Galileo | George Ellery Hale | William Herschel | Edwin Hubble | Jacobus Kapteyn | Johannes Kepler | Gerard Kuiper | Henrietta Leavitt | Isaac Newton | Edward C. Pickering | Ptolemy | Henry Norris Russell | Harlow Shapley
See also
External links
Definitions from Wiktionary
Textbooks from Wikibooks
Quotations from Wikiquote
Source texts from Wikisource
Images and media from Commons
News stories from Wikinews
Learning resources from Wikiversity
