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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The Oort cloud, one of the most successful theoretical models about the Solar System (from Theoretical astronomy) -
Overview of types of observational astronomy by observed wavelengths and their observability. (from Observational astronomy) -
Ultra HD photography taken at La Silla Observatory (from Observational astronomy) -
Sunset at the equinox from the prehistoric site of Pizzo Vento at Fondachelli Fantina, Sicily (from History of astronomy) -
Comparison of CMB (Cosmic microwave background) results from satellites COBE, WMAP and Planck documenting a progress in 1989–2013 (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 Crab Nebula as seen in various wavelengths (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) -
Sir Patrick Moore was one of the world's leading popularisers of astronomy. (from Amateur astronomy) -
9th-century diagram of the positions of the seven planets on 18 March 816, from the Leiden Aratea (from History of astronomy) -
Babylonian tablet in the British Museum recording Halley's Comet in 164 BC (from History of astronomy) -
Places like Paranal Observatory offer crystal clear skies for observing astronomical objects with or without instruments. (from Amateur astronomy) -
Calendrical functions of the Berlin Gold Hat c. 1000 BC (from History of 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) -
The Hubble Space Telescope (from History of astronomy) -
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Arabic astrolabe from 1079 to 1080 AD (from History of 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) -
A map of the southern celestial hemisphere, also by Bayer (from History of astronomy) -
50 cm refracting telescope at Nice Observatory (from Observational 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) -
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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 amateur astrophotography setup with an automated guide system connected to a laptop (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) -
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) -
Historical accuracy of atomic clocks from NIST. (from Theoretical astronomy) -
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) -
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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) -
Amateur astronomy groups are often involved in outreach to introduce astronomy to the general public (from Amateur astronomy) -
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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) -
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) -
ALMA is the world's most powerful telescope for studying the Universe at submillimeter and millimeter wavelengths. (from Observational astronomy) -
Amateur astronomer recording observations of the sun. (from Amateur astronomy)
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Featured article -
Barnard's Star is a small red dwarf star in the constellation of Ophiuchus. At a distance of 5.96 light-years (1.83 pc) from Earth, it is the fourth-nearest-known individual star to the Sun after the three components of the Alpha Centauri system, and is the closest star in the northern celestial hemisphere. Its stellar mass is about 16% of the Sun's, and it has 19% of the Sun's diameter. Despite its proximity, the star has a dim apparent visual magnitude of +9.5 and is invisible to the unaided eye; it is much brighter in the infrared than in visible light.
Barnard's Star is among the most studied red dwarfs because of its proximity and favorable location for observation near the celestial equator. Historically, research on Barnard's Star has focused on measuring its stellar characteristics, its astrometry, and also refining the limits of possible extrasolar planets. Although Barnard's Star is ancient, it still experiences stellar flare events, one being observed in 1998. (Full article...)
Did you know -
- ... that Jerry Nelson is the principal designer and project scientist for the Keck telescopes?
- ... that five supernovae have been found in the Messier 100 spiral galaxy?
- ... that the Antlia Dwarf galaxy may have distorted the shape of its neighbour NGC 3109 one billion years ago?
- ... that AP Columbae, the closest young star known, formed after the dinosaurs became extinct?
- ... that a planet was discovered around the star MOA-2009-BLG-387L after it eclipsed a background star, refracting the star's light in a process called gravitational microlensing?
More Did you know (auto generated)
- ... that Michael Collins has been called "one of the best clarinettists walking the planet" by The Times?
- ... that 1ES 1927+654, a galaxy in Draco, exhibited such extreme nuclear activity that it challenged conventional models of black-hole environments?
- ... that examples of artificial planets in science fiction include Riverworld, the Well World, and the Death Star?
- ... that the galaxy NGC 1700 has a rotating hot gas disk glowing in X-rays after merging with another galaxy three billion years ago?
- ... that a profile of artist Mark Hearld said his "wrens and squirrels, field mice and owls" help a child care about the planet better than telling them it is burning?
- ... that novelist Hal Clement created the planet Mesklin in 1953 based on the real-world suspected detection of an extrasolar planet?
WikiProjects
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The Hubble eXtreme Deep Field (HXDF), released on September 25, 2012, is an image of a portion of space in the center of the Hubble Ultra-Deep Field image. It covers an area of 2.3 arcminutes by 2 arcminutes, or approximately 80% of the area of the HUDF. The HXDF contains approximately 5,500 galaxies, the oldest of which are seen as they were 13.2 billion years ago.
Astronomy News
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- 23 June 2025 –
- The Vera C. Rubin Observatory in Chile releases the first light images from its new 8.4-meter (28 ft) telescope. (Scientific American)
September anniversaries
- 2 September 1988 – Australia Telescope Compact Array (ATCA), which first imaged a radio supernova remnant as it formed, has its first light.
- 5 September 1977 – Space probe Voyager 1 is launched on a mission to study Jupiter and Saturn
- 8 September 1966 – The first episode of a new television science fiction series Star Trek is shown on NBC-TV
- 12 September 2013 – NASA announces that 19 days earlier, Voyager 1 had become the first man-made object to cross the heliopause and enter interstellar space
- 15 September 2017 – The Cassini spacecraft plunges into the atmosphere of Saturn, ending its 13-year tour of the ringed planet
- 21 September 1866 – Science fiction writer, H. G. (Herbert George) Wells is born, in England
- 23 September 1846 – The planet Neptune is discovered by Johann Gottfried Galle using mathematical equations from John Couch Adams and Urbain Le Verrier
- 29 September 1971 – The Orbiting Solar Observatory 7 satellite launches with the first x-ray observations of a beginning solar flare and of solar streamers
Space-related Portals
Astronomical events
All times UT unless otherwise specified. Portal:Astronomy/Events/September 2025
Topics
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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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