Portal:Astronomy
Introduction
Astronomy is a natural science that studies celestial objects and the phenomena that occur in the cosmos. It uses mathematics, physics, and chemistry to explain their origin and their overall evolution. Objects of interest include planets, moons, stars, nebulae, galaxies, meteoroids, asteroids, and comets. Relevant phenomena include supernova explosions, gamma ray bursts, quasars, blazars, pulsars, and cosmic microwave background radiation. More generally, astronomy studies everything that originates beyond Earth's atmosphere. Cosmology is the branch of astronomy that studies the universe as a whole.
Astronomy is one of the oldest natural sciences. The early civilizations in recorded history made methodical observations of the night sky. These include the Egyptians, Babylonians, Greeks, Indians, Chinese, Maya, and many ancient indigenous peoples of the Americas. In the past, astronomy included disciplines as diverse as astrometry, celestial navigation, observational astronomy, and the making of calendars.
Professional astronomy is split into observational and theoretical branches. Observational astronomy is focused on acquiring data from observations of astronomical objects. This data is then analyzed using basic principles of physics. Theoretical astronomy is oriented toward the development of computer or analytical models to describe astronomical objects and phenomena. These two fields complement each other. Theoretical astronomy seeks to explain observational results and observations are used to confirm theoretical results.
Astronomy is one of the few sciences in which amateurs play an active role. This is especially true for the discovery and observation of transient events. Amateur astronomers have helped with many important discoveries, such as finding new comets. (Full article...)
General images -
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ALMA is the world's most powerful telescope for studying the Universe at submillimeter and millimeter wavelengths. (from Observational astronomy) -
History of the Universe – gravitational waves are hypothesized to arise from cosmic inflation, a rapidly accelerated expansion just after the Big Bang (from Physical cosmology) -
An image of the Cat's Paw Nebula created combining the work of professional and amateur astronomers. The image is the combination of the 2.2-metre MPG/ESO telescope of the La Silla Observatory in Chile and a 0.4-meter amateur telescope. (from Amateur astronomy) -
Calendrical functions of the Berlin Gold Hat c. 1000 BC (from History of astronomy) -
A map of the southern celestial hemisphere, also by Bayer (from History of astronomy) -
Sir Patrick Moore was one of the world's leading popularisers of astronomy. (from Amateur astronomy) -
Sunset at the equinox from the prehistoric site of Pizzo Vento at Fondachelli Fantina, Sicily (from History of astronomy) -
9th-century diagram of the positions of the seven planets on 18 March 816, from the Leiden Aratea (from History of astronomy) -
One of the Oldest Observatories in South America is the Quito Astronomical Observatory, founded in 1873 and located 12 minutes south of the Equator in Quito, Ecuador. The Quito Astronomical Observatory is the National Observatory of Ecuador and is located in the Historic Center of Quito and is managed by the National Polytechnic School. (from Observational astronomy) -
The main platform at La Silla hosts a huge range of telescopes with which astronomers can explore the Universe. (from Observational astronomy) -
Arabic astrolabe from 1079 to 1080 AD (from History of astronomy) -
A voting session is conducted in 2006 International Astronomical Union's general assembly for determining a new definition of a planet (from Astronomer) -
The inflationary theory as an augmentation to the Big Bang theory was first proposed by Alan Guth of MIT. Inflation solves the 'horizon problem' by making the early universe much more compact than was assumed in the standard model. Given such smaller size, causal contact (i.e., thermal communication) would have been possible among all regions of the early universe. The image was an adaptation from various generic charts depicting the growth of the size of the observable universe, for both the standard model and inflationary model respectively, of the Big Bang theory. (from Physical cosmology) -
Comparison of CMB (Cosmic microwave background) results from satellites COBE, WMAP and Planck documenting a progress in 1989–2013 (from History of astronomy) -
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The Oort cloud, one of the most successful theoretical models about the Solar System (from Theoretical astronomy) -
Historical accuracy of atomic clocks from NIST. (from Theoretical astronomy) -
50 cm refracting telescope at Nice Observatory (from Observational astronomy) -
Map of the Milky Way Galaxy, with the constellations that cross the galactic plane in each direction and the known prominent components annotated including main arms, spurs, bar, nucleus/bulge, notable nebulae and globular clusters (from History of astronomy) -
Segment of the astronomical ceiling of Senenmut's Tomb (circa 1479–1458 BC), depicting constellations, protective deities, and twenty-four segmented wheels for the hours of the day and the months of the year (from History of astronomy) -
Amateur astronomer recording observations of the sun. (from Amateur astronomy) -
An amateur astrophotography setup with an automated guide system connected to a laptop (from Observational astronomy) -
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Babylonian tablet in the British Museum recording Halley's Comet in 164 BC (from History of astronomy) -
Portrait of the Flemish astronomer Ferdinand Verbiest who became head of the Mathematical Board and director of the Observatory of the Chinese emperor in 1669 (from Astronomer) -
The Crab Nebula as seen in various wavelengths (from Observational astronomy) -
An example of a gravitational lens found in the DESI Legacy Surveys data. There are four sets of lensed images in DESI-090.9854-35.9683, corresponding to four distinct background galaxies—from the outermost giant red arc to the innermost bright blue arc, arranged in four concentric circles. All of them are gravitationally warped—or lensed—by the orange galaxy at the very center. Dark matter is expected to produce gravitational lensing also. (from Physical cosmology) -
Ultra HD photography taken at La Silla Observatory (from Observational astronomy) -
Places like Paranal Observatory offer crystal clear skies for observing astronomical objects with or without instruments. (from Amateur astronomy) -
A map of the northern celestial hemisphere from Johann Bayer's 1661 edition of Uranometria, the first atlas to feature star charts covering the entire celestial sphere (from History of astronomy) -
The Hubble Space Telescope (from History of astronomy) -
Amateur astronomy groups are often involved in outreach to introduce astronomy to the general public (from Amateur astronomy) -
Artist conception of the Big Bang cosmological model, the most widely accepted out of all in physical cosmology (neither time nor size to scale) (from Physical cosmology) -
The Nebra sky disk, Germany, 1800–1600 BC (from History of astronomy) -
Overview of types of observational astronomy by observed wavelengths and their observability. (from Observational astronomy) -
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Featured article -
The definition of the term planet has changed several times since the word was coined by the ancient Greeks. Greek astronomers employed the term ἀστέρες πλανῆται (asteres planetai), 'wandering stars', for star-like objects which apparently moved over the sky. Over the millennia, the term has included a variety of different celestial bodies, from the Sun and the Moon to satellites and asteroids.
In modern astronomy, there are two primary conceptions of a planet. A planet can be an astronomical object that dynamically dominates its region (that is, whether it controls the fate of other smaller bodies in its vicinity) or it is defined to be in hydrostatic equilibrium (it has become gravitationally rounded and compacted). These may be characterized as the dynamical dominance definition and the geophysical definition. (Full article...)
Did you know -
- ... that the Lyman-alpha blob 1 is a blob of gas 300,000 light-years across located some 11.5 billion light-years from Earth?
- ... that 51 Ophiuchi has a disk of dust and gas that is likely a planetary system in the late stages of formation?
- ... that the Magellan Planet Search Program has discovered five eccentric Jupiter-mass extra-solar planets since the program started gathering data in December 2002?
- ... that asteroids with two moons, like 1994 CC, comprise only 1% of the near-Earth objects?
- ... that pictures by amateur astrophotographer Steve Mandel help to explore faint nebulae of the Milky Way?
More Did you know (auto generated)
- ... that examples of artificial planets in science fiction include Riverworld, the Well World, and the Death Star?
- ... that the majority of extrasolar planets in fiction are inhabited by native species?
- ... that novelist Hal Clement created the planet Mesklin in 1953 based on the real-world suspected detection of an extrasolar planet?
- ... that a group of K-pop fans performed a dance with the goal of convincing a company to commit to 100% renewable energy?
- ... that the active galaxy 3C 120 was given the variable-star designation BW Tauri because of its variability in the visible spectrum?
- ... that the Springfield Science Museum is home to the oldest operating projection planetarium in the United States?
WikiProjects
Selected image -
Geodynamics of Venus as seen from a global radar view of the surface from Magellan probe radar imaging between 1990 and 1994. The age of Venus was revealed by the observation of over 900 impact craters on the surface of the planet.
Astronomy News
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- The Vera C. Rubin Observatory in Chile releases the first light images from its new 8.4-meter (28 ft) telescope. (Scientific American)
October anniversaries
- 1 October 2003 – The Japan Aerospace Exploration Agency is formed from a merger of three previous Japanese space agencies
- 4 October 1957 – The first artificial satellite, Sputnik 1, is launched into orbit by the Soviet Union, triggering the Space Race
- 5 October 2012 – CSIRO's Australian Square Kilometre Array Pathfinder (ASKAP) telescope, which detected the first Odd radio circle in 2019, has its first light.
- 15 October 1997 – The Cassini space probe launches and is active in space for nearly 20 years
- 15 October 2003 – The People's Republic of China becomes the third nation to send a human into space when Yang Liwei is launched into outer space aboard Shenzhou 5
- 24 October 1946 – First motion pictures of Earth are taken from a V-2 rocket
- 29 October 1991 – Galileo probe flyby of Asteroid Gaspra
- 31 October 1961 – Murriyang, CSIRO's 64 m Parkes radio telescope at the Parkes Observatory on Wiradjuri Country in NSW, was inaugurated.
Space-related Portals
Astronomical events
All times UT unless otherwise specified. Portal:Astronomy/Events/October 2025
Topics
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Subcategories
Things you can do
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Wikibooks
These books may be in various stages of development. See also the related Science and Mathematics bookshelves.
- Astronomy
- GAT: A Glossary of Astronomical Terms
- Introduction to Astrophysics
- General relativity
- Observing the Sky from 30°S
- Observing the Sky from 40°N
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