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 1Southern Hemisphere (from History of astronomy)
Image 2Sunset at the equinox from the prehistoric site of Pizzo Vento at Fondachelli Fantina, Sicily (from History of astronomy)
Image 3The Oort cloud, one of the most successful theoretical models about the Solar System (from Theoretical astronomy)
Image 4Babylonian tablet in the British Museum recording Halley's Comet in 164 BC (from History of astronomy)
Image 5Calendrical functions of the Berlin Gold Hat c. 1000 BC (from History of astronomy)
Image 6One 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 7The 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 8An assembly in Estonia to observe meteors (from Observational astronomy)
Image 9Segment 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 10Mayall telescope at Kitt Peak National Observatory (from Observational astronomy)
Image 11The Hubble Space Telescope (from History of astronomy)
Image 12An 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 13Places like Paranal Observatory offer crystal clear skies for observing astronomical objects with or without instruments. (from Amateur astronomy)
Image 14Arabic astrolabe from 1079 to 1080 AD (from History of astronomy)
Image 15Amateur astronomer recording observations of the sun. (from Amateur astronomy)
Image 16Amateur astronomy groups are often involved in outreach to introduce astronomy to the general public (from Amateur astronomy)
Image 17History 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 18Portrait 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 19Artist 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 20Historical accuracy of atomic clocks from NIST. (from Theoretical astronomy)
Image 21The Nebra sky disk, Germany, 1800–1600 BC (from History of astronomy)
Image 22The 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 23ALMA is the world's most powerful telescope for studying the Universe at submillimeter and millimeter wavelengths. (from Observational astronomy)
$Image 2450 cm refracting telescope at Nice Observatory (from Observational astronomy)$

Image 2450 cm refracting telescope at Nice Observatory (from Observational astronomy)
Image 25Historical Jantar Mantar observatory in Jaipur, India (from History of astronomy)
Image 26The Crab Nebula as seen in various wavelengths (from Observational astronomy)
Image 27Overview of types of observational astronomy by observed wavelengths and their observability. (from Observational astronomy)
Image 28Comparison of CMB (Cosmic microwave background) results from satellites COBE, WMAP and Planck documenting a progress in 1989–2013 (from History of astronomy)
Image 29Map 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 309th-century diagram of the positions of the seven planets on 18 March 816, from the Leiden Aratea (from History of astronomy)
Image 31Sir Patrick Moore was one of the world's leading popularisers of astronomy. (from Amateur astronomy)
Image 32The main platform at La Silla hosts a huge range of telescopes with which astronomers can explore the Universe. (from Observational astronomy)
Image 33"El Caracol" observatory temple at Chichen Itza, Mexico (from History of astronomy)
Image 34A voting session is conducted in 2006 International Astronomical Union's general assembly for determining a new definition of a planet (from Astronomer)
Image 35Ultra HD photography taken at La Silla Observatory (from Observational astronomy)
Image 36An amateur astrophotography setup with an automated guide system connected to a laptop (from Observational astronomy)
Image 37The Antikythera Mechanism was an analog computer from 150 to 100 BC designed to calculate the positions of astronomical objects. (from History of astronomy)
Image 38An 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)

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

False color Hubble Space Telescope WFPC2 image taken in 2013. The bright lines are diffraction spikes.

Proxima Centauri is the nearest star to Earth after the Sun, located 4.25 light-years away in the southern constellation of Centaurus. This object was discovered in 1915 by Robert Innes. It is a small, low-mass star, too faint to be seen with the naked eye, with an apparent magnitude of 11.13. Its Latin name means the 'nearest [star] of Centaurus'. Proxima Centauri is a member of the Alpha Centauri star system, being identified as component Alpha Centauri C, and is 2.18° to the southwest of the Alpha Centauri AB pair. It is currently 12,950 AU (0.2 ly) from AB, which it orbits with a period of about 550,000 years.

Proxima Centauri is a red dwarf star with a mass about 12.5% of the Sun's mass (M_☉), and average density about 33 times that of the Sun. Because of Proxima Centauri's proximity to Earth, its angular diameter can be measured directly. Its actual diameter is about one-seventh (14%) the diameter of the Sun. Although it has a very low average luminosity, Proxima Centauri is a flare star that randomly undergoes dramatic increases in brightness because of magnetic activity. The star's magnetic field is created by convection throughout the stellar body, and the resulting flare activity generates a total X-ray emission similar to that produced by the Sun. The internal mixing of its fuel by convection through its core and Proxima's relatively low energy-production rate, mean that it will be a main-sequence star for another four trillion years. (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?

More Did you know facts

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... that Michael Collins has been called "one of the best clarinettists walking the planet" by The Times?
... 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 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 Passive Seismic Experiment Package recorded one of the first instances of humans littering on another planetary body?
... 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 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 / ESA / Michael E. Brown

Eris (minor planet designation 136199 Eris) is the most massive and second-largest known dwarf planet in the Solar System. Image of Eris (center) and Dysnomia (left of center), taken by the Hubble Space Telescope

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Astronomy News

21 November 2024 –: The European Southern Observatory announces that its astronomers in Chile capture the first close-up image of a star outside the Milky Way. (The New York Times)
20 November 2024 – Discoveries of exoplanets: In a study published by the Nature journal, astronomers announce the discovery of IRAS 04125+2902 b, a newborn exoplanet. The discovery was made by Madyson Barber, a graduate student at the University of North Carolina at Chapel Hill. (Nature) (ABC 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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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

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Space-related Portals

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Astronomical events

All times UT unless otherwise specified.

1 December, 06:21	New moon
6 December, 02:11	Mercury at inferior conjunction
7 December, 20:19	Jupiter at opposition
8 December, 08:56	Moon occults Saturn
9 December, 09:19	Moon occults Neptune
12 December, 13:18	Moon at perigee
14 December, 01:12	Geminids peak
15 December, 09:02	Full moon
18 December, 08:49	Moon occults Mars
21 December, 09:20	Earth southern solstice
22 December, 10:00	Ursids peak
24 December, 07:25	Moon at apogee
25 December, 01:59	Mercury at greatest western elongation
30 December, 22:27	New moon