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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...)

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

Image 1The Nebra sky disk, Germany, 1800 - 1600 BC (from History of astronomy)
Image 2Segment of the astronomical ceiling of Senenmut's Tomb (circa 1479–1458 BCE), 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 3Amateur astronomer recording observations of the sun. (from Amateur astronomy)
Image 4An 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 5The 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 6Historical accuracy of atomic clocks from NIST. (from Theoretical astronomy)
Image 7Sunset at the equinox from the prehistoric site of Pizzo Vento at Fondachelli Fantina, Sicily (from History of astronomy)
Image 8Historical Jantar Mantar observatory in Jaipur, India (from History of astronomy)
Image 9Map 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)
Image 10Artist 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 11Amateur astronomy groups are often involved in outreach in order to introduce astronomy to the general public (from Amateur astronomy)
Image 12The Crab Nebula as seen in various wavelengths (from Observational astronomy)
Image 13Portrait 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 14Places like Paranal Observatory offer crystal clear skies for observing astronomical objects with or without instruments. (from Amateur astronomy)
Image 15Overview of types of observational astronomy by observed wavelengths and their observability. (from Observational astronomy)
Image 16An assembly in Estonia to observe meteors (from Observational astronomy)
Image 17Ultra HD photography taken at La Silla Observatory (from Observational astronomy)
Image 189th-century diagram of the positions of the seven planets on 18 March 816, from the Leiden Aratea (from History of astronomy)
Image 19History 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 20A voting session is conducted in 2006 International Astronomical Union's general assembly for determining a new definition of a planet (from Astronomer)
Image 21One 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)
$Image 2250 cm refracting telescope at Nice Observatory (from Observational astronomy)$

Image 2250 cm refracting telescope at Nice Observatory (from Observational astronomy)
Image 23The main platform at La Silla hosts a huge range of telescopes with which astronomers can explore the Universe. (from Observational astronomy)
Image 24The Antikythera Mechanism was an analog computer from 150 to 100 BC designed to calculate the positions of astronomical objects. (from History of astronomy)
Image 25"El Caracol" observatory temple at Chichen Itza, Mexico (from History of astronomy)
Image 26Babylonian tablet in the British Museum recording Halley's comet in 164 BC (from History of astronomy)
Image 27Sir Patrick Moore was one of the world's leading popularisers of astronomy. (from Amateur astronomy)
Image 28The Oort cloud, one of the most successful theoretical model about the Solar System (from Theoretical astronomy)
Image 29Southern Hemisphere (from History of astronomy)
Image 30Mayall telescope at Kitt Peak National Observatory (from Observational astronomy)
Image 31Calendrical functions of the Berlin Gold Hat c. 1000 BC (from History of astronomy)
Image 32An amateur astrophotography setup with an automated guide system connected to a laptop (from Observational astronomy)
Image 33The Hubble Space Telescope (from History of astronomy)
Image 34ALMA is the world's most powerful telescope for studying the Universe at submillimeter and millimeter wavelengths. (from Observational astronomy)
Image 35Arabic astrolabe from 1079 to 1080 AD (from History of astronomy)
Image 36Comparison 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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This is a Featured article, which represents some of the best content on English Wikipedia.

The Kuiper belt (/ˈkaɪpər/ KY-pər) is a circumstellar disc in the outer Solar System, extending from the orbit of Neptune at 30 astronomical units (AU) to approximately 50 AU from the Sun. It is similar to the asteroid belt, but is far larger—20 times as wide and 20–200 times as massive. Like the asteroid belt, it consists mainly of small bodies or remnants from when the Solar System formed. While many asteroids are composed primarily of rock and metal, most Kuiper belt objects are composed largely of frozen volatiles (termed "ices"), such as methane, ammonia, and water. The Kuiper belt is home to most of the objects that astronomers generally accept as dwarf planets: Orcus, Pluto, Haumea, Quaoar, and Makemake. Some of the Solar System's moons, such as Neptune's Triton and Saturn's Phoebe, may have originated in the region.

The Kuiper belt is named in honor of the Dutch astronomer Gerard Kuiper, who conjectured the existence of the belt in 1951. There were researchers before and after him who also speculated on its existence, such as Kenneth Edgeworth in the 1930s. The astronomer Julio Angel Fernandez published a paper in 1980 suggesting the existence of a comet belt beyond Neptune which could serve as a source for short-period comets. (Full article...)

List of featured articles

Did you know - show different entries

... that Caroline Moore was 14 years old when she discovered supernova 2008ha?
... that although Charles Messier discovered the galaxy M91 in 1781, it was added to his catalogue only two centuries later?
... that the fall of the Neuschwanstein meteorite in 2002 was observed by the European Fireball Network and outdoor witnesses through most of Central Europe?
... that AG Pegasi has been described as the slowest nova ever recorded?

More Did you know facts

More Did you know (auto generated)

... that fictional depictions of Jupiter have portrayed human habitation on the planet and its moons both by altering the environment to suit humans and altering humans to be suited to the environment?
... that the Springfield Science Museum is home to the oldest operating projection planetarium in the United States?
... that Michael Collins has been called "one of the best clarinettists walking the planet" by The Times?
... that examples of artificial planets in science fiction include Riverworld, the Well World, and the Death Star?
... 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 the active galaxy 3C 120 was given the variable-star designation BW Tauri because of its variability in the visible spectrum?

WikiProjects

WikiProject Astronomy	WikiProject Solar System



WikiProject Cosmology	WikiProject Spaceflight

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Credit: NVN271

Alpha Herculis is a multiple star system in the constellation of Hercules. A view of Alpha Herculis in a small telescope. The components A and B are resolved with angular separation of 4.64'' (in 2020).

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Astronomy News

20 February 2024 –: Astronomers identify the most luminous object ever observed, QSO J0529-4351, a quasar that accretes around one solar mass per day. (The Guardian) (Nature.com)
24 November 2023 –: Astronomers at the Telescope Array Project in Utah, United States, observe the second largest cosmic ray ever detected, the so-called Amaterasu particle, with an energy of 244 EeV. (Cosmos Magazine)

April anniversaries

2 April 1968 – The epic science fiction film, 2001: A Space Odyssey is released
3 April 2014 – NASA announces that the Cassini orbiter has found evidence of an underground body of water on Enceladus, a moon of Saturn
7 April 2001 – Mars Odyssey orbiter is launched to map and search for water on Mars
12 April 1961 – Cosmonaut Yuri Gagarin becomes the first human to enter outer space when he is launched into orbital flight in Vostok 1
19 April 1971 – The first space station, Salyut 1, is launched into orbit
24 April 1990 – The Hubble Space Telescope, a powerful research tool and public relations boon for astronomy, is launched into orbit

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Space-related Portals

Astronomical events

All times UT unless otherwise specified.

6 April, 09:25	Moon occults Saturn
7 April, 08:11	Moon occults Neptune
7 April, 16:47	Moon occults Venus
7 April, 17:53	Moon at perigee
8 April, 18:18	New moon and Total Solar Eclipse
11 April, 22:53	Mercury at inferior conjunction
20 April, 02:09	Moon at apogee
22 April, 06:44	Lyrids peak
23 April, 23:49	Full moon