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 1One 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 2Artist 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 3The Crab Nebula as seen in various wavelengths (from Observational astronomy)
Image 4A voting session is conducted in 2006 International Astronomical Union's general assembly for determining a new definition of a planet (from Astronomer)
Image 5The main platform at La Silla hosts a huge range of telescopes with which astronomers can explore the Universe. (from Observational astronomy)
Image 6"El Caracol" observatory temple at Chichen Itza, Mexico (from History of astronomy)
Image 7Map 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 8Amateur astronomer recording observations of the sun. (from Amateur astronomy)
Image 9Southern Hemisphere (from History of astronomy)
Image 109th-century diagram of the positions of the seven planets on 18 March 816, from the Leiden Aratea (from History of astronomy)
Image 11History 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 12Calendrical functions of the Berlin Gold Hat c. 1000 BC (from History of astronomy)
Image 13Segment 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 14The Oort cloud, one of the most successful theoretical models about the Solar System (from Theoretical astronomy)
Image 15Places like Paranal Observatory offer crystal clear skies for observing astronomical objects with or without instruments. (from Amateur astronomy)
$Image 1650 cm refracting telescope at Nice Observatory (from Observational astronomy)$

Image 1650 cm refracting telescope at Nice Observatory (from Observational astronomy)
Image 17An 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 18Mayall telescope at Kitt Peak National Observatory (from Observational astronomy)
Image 19Portrait 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 20The Antikythera Mechanism was an analog computer from 150 to 100 BC designed to calculate the positions of astronomical objects. (from History of astronomy)
Image 21The Nebra sky disk, Germany, 1800–1600 BC (from History of astronomy)
Image 22Ultra HD photography taken at La Silla Observatory (from Observational astronomy)
Image 23Amateur astronomy groups are often involved in outreach to introduce astronomy to the general public (from Amateur astronomy)
Image 24The Hubble Space Telescope (from History of astronomy)
Image 25Historical accuracy of atomic clocks from NIST. (from Theoretical astronomy)
Image 26Sir Patrick Moore was one of the world's leading popularisers of astronomy. (from Amateur astronomy)
Image 27Sunset at the equinox from the prehistoric site of Pizzo Vento at Fondachelli Fantina, Sicily (from History of astronomy)
Image 28Historical Jantar Mantar observatory in Jaipur, India (from History of astronomy)
Image 29An assembly in Estonia to observe meteors (from Observational astronomy)
Image 30Arabic astrolabe from 1079 to 1080 AD (from History of astronomy)
Image 31The 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)
Image 32An amateur astrophotography setup with an automated guide system connected to a laptop (from Observational astronomy)
Image 33Overview of types of observational astronomy by observed wavelengths and their observability. (from Observational astronomy)
Image 34Babylonian tablet in the British Museum recording Halley's Comet in 164 BC (from History of astronomy)
Image 35The 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 36Comparison of CMB (Cosmic microwave background) results from satellites COBE, WMAP and Planck documenting a progress in 1989–2013 (from History of astronomy)
Image 37An 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)
Image 38ALMA is the world's most powerful telescope for studying the Universe at submillimeter and millimeter wavelengths. (from Observational astronomy)

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

Image of the Sun, a G-type main-sequence star, the closest to Earth

A star is a luminous spheroid of plasma held together by self-gravity. The nearest star to Earth is the Sun. Many other stars are visible to the naked eye at night; their immense distances from Earth make them appear as fixed points of light. The most prominent stars have been categorised into constellations and asterisms, and many of the brightest stars have proper names. Astronomers have assembled star catalogues that identify the known stars and provide standardized stellar designations. The observable universe contains an estimated 10²² to 10²⁴ stars. Only about 4,000 of these stars are visible to the naked eye—all within the Milky Way galaxy.

A star's life begins with the gravitational collapse of a gaseous nebula of material largely comprising hydrogen, helium, and trace heavier elements. Its total mass mainly determines its evolution and eventual fate. A star shines for most of its active life due to the thermonuclear fusion of hydrogen into helium in its core. This process releases energy that traverses the star's interior and radiates into outer space. At the end of a star's lifetime as a fusor, its core becomes a stellar remnant: a white dwarf, a neutron star, or—if it is sufficiently massive—a black hole. (Full article...)

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Did you know - show different entries

... that Abell 2142, a galaxy cluster, is one of the most massive objects in the universe?
... that a jet from one of the component stars of Z Canis Majoris is over 11 light-years long?
... that Messier 58 is one of the brightest galaxies in the Virgo Cluster and is 1 of 4 barred spiral galaxies included in Charles Messier's catalog?
... that the asteroid 2014 AA entered Earth's atmosphere on the early morning of January 2, 2014, less than a day after it was discovered?
... that ATIC, a balloon-borne detector flying over Antarctica, recently found excess cosmic ray electrons that might provide evidence for dark matter consisting of Kaluza-Klein particles?
.... that the Sun fuses about 620 million metric tons of hydrogen per seconds due to Gravity?

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... 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 Susan Murabana created Africa's first permanent planetarium?
... 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 in early depictions of Uranus in fiction, the planet was portrayed as solid

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WikiProjects

WikiProject Astronomy	WikiProject Solar System



WikiProject Cosmology	WikiProject Spaceflight

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Credit: NASA / JPL-Caltech / Space Science Institute

Mimas is a moon of Saturn. It was discovered in 1789 by William Herschel, after whom the large crater in the image is named. It is the twentieth-largest moon in the Solar System, and the smallest astronomical body that is known to be rounded in shape because of self-gravitation. This photograph of Mimas was taken by the unmanned spacecraft Cassini in 2010.

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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

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Space-related Portals

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Astronomical events

All times UT unless otherwise specified.

3 September, 01:55	New moon
5 September, 01:59	Mercury at greatest western elongation
5 September, 10:16	Moon occults Venus
5 September, 14:55	Moon at apogee
8 September, 03:54	Saturn at opposition
17 September, 10:22	Moon occults Saturn
18 September, 02:44	Full moon and partial lunar eclipse
18 September, 07:35	Moon occults Neptune
18 September, 13:26	Moon at perigee
20 September, 22:43	Neptune at opposition
22 September, 12:44	Earth southward equinox
30 September, 20:59	Mercury at superior conjunction