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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Sunset at the equinox from the prehistoric site of Pizzo Vento at Fondachelli Fantina, Sicily (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) -
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) -
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) -
Amateur astronomy groups are often involved in outreach to introduce astronomy to the general public (from Amateur astronomy) -
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Comparison of CMB (Cosmic microwave background) results from satellites COBE, WMAP and Planck documenting a progress in 1989–2013 (from History of astronomy) -
A map of the southern celestial hemisphere, also by Bayer (from History of astronomy) -
Historical accuracy of atomic clocks from NIST. (from Theoretical astronomy) -
British astronomer Sir Patrick Moore (from Astronomer) -
Babylonian tablet in the British Museum recording Halley's Comet in 164 BC (from History of 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) -
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) -
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) -
The Nebra sky disk, Germany, 1800–1600 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) -
Overview of types of observational astronomy by observed wavelengths and their observability. (from Observational astronomy) -
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Ultra HD photography taken at La Silla Observatory (from Observational astronomy) -
Arabic astrolabe from 1079 to 1080 AD (from History of 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) -
9th-century diagram of the positions of the seven planets on 18 March 816, from the Leiden Aratea (from History of astronomy) -
Calendrical functions of the Berlin Gold Hat c. 1000 BC (from History of astronomy) -
Amateur astronomer recording observations of the sun. (from Amateur astronomy) -
ALMA is the world's most powerful telescope for studying the Universe at submillimeter and millimeter wavelengths. (from Observational astronomy) -
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The Oort cloud, one of the most successful theoretical models about the Solar System (from Theoretical 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) -
An amateur astrophotography setup with an automated guide system connected to a laptop (from Observational astronomy) -
50 cm refracting telescope at Nice Observatory (from Observational astronomy) -
The Hubble Space Telescope (from History of astronomy) -
Places like Paranal Observatory offer crystal clear skies for observing astronomical objects with or without instruments. (from Amateur astronomy) -
The Crab Nebula as seen in various wavelengths (from Observational 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) -
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)
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Featured article -
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Herbig–Haro (HH) objects are bright patches of nebulosity associated with newborn stars. They are formed when narrow jets of partially ionised gas ejected by stars collide with nearby clouds of gas and dust at several hundred kilometers per second. Herbig–Haro objects are commonly found in star-forming regions, and several are often seen around a single star, aligned with its rotational axis. Most of them lie within about one parsec (3.26 light-years) of the source, although some have been observed several parsecs away. HH objects are transient phenomena that last around a few tens of thousands of years. They can change visibly over timescales of a few years as they move rapidly away from their parent star into the gas clouds of interstellar space (the interstellar medium or ISM). Hubble Space Telescope observations have revealed the complex evolution of HH objects over the period of a few years, as parts of the nebula fade while others brighten as they collide with the clumpy material of the interstellar medium.
First observed in the late 19th century by Sherburne Wesley Burnham, Herbig–Haro objects were recognised as a distinct type of emission nebula in the 1940s. The first astronomers to study them in detail were George Herbig and Guillermo Haro, after whom they have been named. Herbig and Haro were working independently on studies of star formation when they first analysed the objects, and recognised that they were a by-product of the star formation process. Although HH objects are visible-wavelength phenomena, many remain invisible at these wavelengths due to dust and gas, and can only be detected at infrared wavelengths. Such objects, when observed in near-infrared, are called molecular hydrogen emission-line objects (MHOs). (Full article...)
Did you know -
- ... that British mathematician Margaret Meyer was the first woman to be elected to the Royal Astronomical Society?
- ... that the star cluster Messier 103 can be observed with the use of binoculars?
- ... that NASA has plans to tug an asteroid to the Moon?
- ... that MOA-2009-BLG-387Lb is the eleventh planet discovered using the gravitational microlensing phenomenon?
- ... that the first Dutch satellite, the Astronomical Netherlands Satellite, had the Main Belt asteroid 9996 ANS named after it?
More Did you know (auto generated)
- ... 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?
- ... that the Springfield Science Museum is home to the oldest operating projection planetarium in the United States?
- ... that in many works of fiction, the asteroid belt is the remnants of a destroyed planet?
- ... that one night on the planet Venus lasts just over 58 full days on Earth?
- ... that the majority of extrasolar planets in fiction are inhabited by native species?
WikiProjects
Selected image -
Abell 2199 is a galaxy cluster in the Abell catalogue featuring a brightest cluster galaxy NGC 6166, a cD galaxy. Abell 2199, located in the Hercules constellation, is the definition of a Bautz-Morgan type I cluster due to NGC 6166.
Astronomy News
- 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)
December anniversaries
- 7 December 1972 – The Blue Marble photograph is taken by the Apollo 17 crew
- 8 December 1992 – Galileo completes the second Earth flyby
- 14 December 1962 – Mariner 2 becomes the first space probe to perform a flyby of a planet, when it passes within 35,000 kilometers of Venus
- 17 December 1917 – 2001: A Space Odyssey science fiction author Arthur C. Clarke is born
- 19 December 2013 – Gaia is launched for the mission to study billions of stars in the Milky Way
- 21 December 1968 – Apollo 8, is launched with the first crewed spacecraft to leave Earth orbit, reach the Moon, orbit it, and return safely to Earth
- 27 December 1571 – Astronomer, mathematician, and astrologer Johannes Kepler is born
Space-related Portals
Astronomical events
All times UT unless otherwise specified. Portal:Astronomy/Events/December 2025
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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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