Portal:Astronomy

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The Astronomy Portal

Introduction

Astronomy is a natural science that studies celestial objects and the phenomena that occur in the cosmos. It uses mathematics, physics, and chemistry in order 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 a 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 - load new batch

The following are images from various astronomy-related articles on Wikipedia.

Image 1Segment 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)
Image 2Sir Patrick Moore was one of the world's leading popularisers of astronomy. (from Amateur astronomy)
Image 3Ultra HD photography taken at La Silla Observatory (from Observational astronomy)
Image 4Arabic astrolabe from 1079 to 1080 AD (from History of astronomy)
Image 5Amateur astronomer recording observations of the sun. (from Amateur astronomy)
Image 6Calendrical functions of the Berlin Gold Hat c. 1000 BC (from History of astronomy)
Image 7Comparison of CMB (Cosmic microwave background) results from satellites COBE, WMAP and Planck documenting a progress in 1989–2013 (from History of astronomy)
Image 8The Northern Hemisphere page from Johann Bayer's 1661 edition of Uranometria - the first atlas to have star charts covering the entire celestial sphere (from History of astronomy)
Image 9Babylonian tablet in the British Museum recording Halley's Comet in 164 BC (from History of astronomy)
Image 10Historical Jantar Mantar observatory in Jaipur, India (from History of astronomy)
Image 119th-century diagram of the positions of the seven planets on 18 March 816, from the Leiden Aratea (from History of astronomy)
Image 12Amateur astronomy groups are often involved in outreach to introduce astronomy to the general public (from Amateur astronomy)
Image 13Mayall telescope at Kitt Peak National Observatory (from Observational astronomy)
Image 14The Oort cloud, one of the most successful theoretical models about the Solar System (from Theoretical astronomy)
Image 15An 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)
Image 16Portrait 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)
Image 17The Crab Nebula as seen in various wavelengths (from Observational astronomy)
Image 18Overview of types of observational astronomy by observed wavelengths and their observability. (from Observational astronomy)
Image 19ALMA is the world's most powerful telescope for studying the Universe at submillimeter and millimeter wavelengths. (from Observational astronomy)
Image 20Historical accuracy of atomic clocks from NIST. (from Theoretical astronomy)
Image 21Artist 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)
$Image 2250 cm refracting telescope at Nice Observatory (from Observational astronomy)$

Image 2250 cm refracting telescope at Nice Observatory (from Observational astronomy)
Image 23An amateur astrophotography setup with an automated guide system connected to a laptop (from Observational astronomy)
Image 24One 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)
Image 25A voting session is conducted in 2006 International Astronomical Union's general assembly for determining a new definition of a planet (from Astronomer)
Image 26"El Caracol" observatory temple at Chichen Itza, Mexico (from History of astronomy)
Image 27Places like Paranal Observatory offer crystal clear skies for observing astronomical objects with or without instruments. (from Amateur astronomy)
Image 28The Hubble Space Telescope (from History of astronomy)
Image 29Southern Hemisphere (from History of astronomy)
Image 30Sunset at the equinox from the prehistoric site of Pizzo Vento at Fondachelli Fantina, Sicily (from History of astronomy)
Image 31History of the Universe – gravitational waves are hypothesized to arise from cosmic inflation, a rapidly accelerated expansion just after the Big Bang (from Physical cosmology)
Image 32The Nebra sky disk, Germany, 1800–1600 BC (from History of astronomy)
Image 33The main platform at La Silla hosts a huge range of telescopes with which astronomers can explore the Universe. (from Observational astronomy)
Image 34The Antikythera Mechanism was an analog computer from 150 to 100 BC designed to calculate the positions of astronomical objects. (from History of astronomy)
Image 35An assembly in Estonia to observe meteors (from Observational astronomy)
Image 36Map 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)

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Featured article - show another

This is a Featured article, which represents some of the best content on English Wikipedia.

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 body 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...)

List of featured articles

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Did you know - show different entries

... that light echoes appear to exceed the speed of light due to simple interstellar illusions?
... that the Leo IV dwarf galaxy is one of the smallest satellites of the Milky Way?
... that a hydrocarbon lake on Saturn's moon Titan and an active volcano on Jupiter's moon Io are among the Solar System features named after deities from Māori mythology?
... that the Local Void is an empty region of space, devoid of matter, lying adjacent to our own Milky Way galaxy?
... that William Herschel's 40-foot telescope was the largest telescope in the world for 50 years?

More Did you know facts

More Did you know (auto generated)

... that King Gizzard & the Lizard Wizard's "cli-fi" thrash metal album addresses a mix of current ecological threats and attempts to find another planet to live on?
... that examples of artificial planets in science fiction include Riverworld, the Well World, and the Death Star?
... that the Passive Seismic Experiment Package recorded one of the first instances of humans littering on another planetary body?
... that in many works of fiction, the asteroid belt is the remnants of a destroyed planet?
... that Kim Ye-ji's performance in the 10 meter air pistol at the 2024 Summer Olympics led her to be dubbed the "coolest person on the planet"?
... that the active galaxy 3C 120 was given the variable-star designation BW Tauri because of its variability in the visible spectrum?

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WikiProjects

WikiProject Astronomy	WikiProject Solar System



WikiProject Cosmology	WikiProject Spaceflight

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Selected image - show another

Credit: NASA / ESA / M. Robberto (Space Telescope Science Institute/ESA) / Hubble Space Telescope Orion Treasury Project Team

The Orion Nebula (also known as Messier 42, M42, or NGC 1976) is a diffuse nebula situated in the Milky Way, being south of Orion's Belt in the constellation of Orion. It is one of the brightest nebulae, visible to the naked eye in the night sky. The entire Orion Nebula in a composite image of visible light and infrared; taken by Hubble Space Telescope in 2006

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Astronomy News

15 July 2024 – Mare Tranquillitatis pit: In the journal Nature Astronomy, American and Italian scientists announce the discovery of a lunar cave, approximately 250 miles (400 km) from the landing site of Apollo 11. (AP) (Nature Astronomy)

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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