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 1The Nebra sky disk, Germany, 1800–1600 BC (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 3Portrait 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 4Mayall telescope at Kitt Peak National Observatory (from Observational astronomy)
Image 5Comparison of CMB (Cosmic microwave background) results from satellites COBE, WMAP and Planck documenting a progress in 1989–2013 (from History of astronomy)
Image 6The Antikythera Mechanism was an analog computer from 150 to 100 BC designed to calculate the positions of astronomical objects. (from History of astronomy)
Image 7History 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 89th-century diagram of the positions of the seven planets on 18 March 816, from the Leiden Aratea (from History of astronomy)
Image 9An amateur astrophotography setup with an automated guide system connected to a laptop (from Observational 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 11The main platform at La Silla hosts a huge range of telescopes with which astronomers can explore the Universe. (from Observational astronomy)
Image 12The 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 13The Crab Nebula as seen in various wavelengths (from Observational astronomy)
Image 14Southern Hemisphere (from History of astronomy)
Image 15The 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 16Calendrical functions of the Berlin Gold Hat c. 1000 BC (from History of astronomy)
Image 17Amateur astronomy groups are often involved in outreach to introduce astronomy to the general public (from Amateur astronomy)
Image 18Map 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)
$Image 1950 cm refracting telescope at Nice Observatory (from Observational astronomy)$

Image 1950 cm refracting telescope at Nice Observatory (from Observational astronomy)
Image 20One 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 21Segment 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 22Babylonian tablet in the British Museum recording Halley's Comet in 164 BC (from History of astronomy)
Image 23The Hubble Space Telescope (from History of astronomy)
Image 24Sir Patrick Moore was one of the world's leading popularisers of astronomy. (from Amateur 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 26Places like Paranal Observatory offer crystal clear skies for observing astronomical objects with or without instruments. (from Amateur astronomy)
Image 27Ultra HD photography taken at La Silla Observatory (from Observational astronomy)
Image 28Amateur astronomer recording observations of the sun. (from Amateur astronomy)
Image 29The Oort cloud, one of the most successful theoretical models about the Solar System (from Theoretical astronomy)
Image 30Historical Jantar Mantar observatory in Jaipur, India (from History of astronomy)
Image 31ALMA is the world's most powerful telescope for studying the Universe at submillimeter and millimeter wavelengths. (from Observational astronomy)
Image 32Arabic astrolabe from 1079 to 1080 AD (from History of astronomy)
Image 33Historical accuracy of atomic clocks from NIST. (from Theoretical astronomy)
Image 34An 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 35"El Caracol" observatory temple at Chichen Itza, Mexico (from History of astronomy)
Image 36An 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 37An assembly in Estonia to observe meteors (from Observational astronomy)
Image 38Overview of types of observational astronomy by observed wavelengths and their observability. (from Observational astronomy)

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Featured article - show another

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

NGC 4414, a typical spiral galaxy in the constellation Coma Berenices, is about 55,000 light-years in diameter and approximately 60 million light-years from Earth.

A galaxy is a system of stars, stellar remnants, interstellar gas, dust, and dark matter bound together by gravity. The word is derived from the Greek galaxias (γαλαξίας), literally 'milky', a reference to the Milky Way galaxy that contains the Solar System. Galaxies, averaging an estimated 100 million stars, range in size from dwarfs with less than a thousand stars, to the largest galaxies known – supergiants with one hundred trillion stars, each orbiting its galaxy's center of mass. Most of the mass in a typical galaxy is in the form of dark matter, with only a few percent of that mass visible in the form of stars and nebulae. Supermassive black holes are a common feature at the centres of galaxies.

Galaxies are categorised according to their visual morphology as elliptical, spiral, or irregular. The Milky Way is an example of a spiral galaxy. It is estimated that there are between 200 billion (2×10¹¹) to 2 trillion galaxies in the observable universe. Most galaxies are 1,000 to 100,000 parsecs in diameter (approximately 3,000 to 300,000 light years) and are separated by distances in the order of millions of parsecs (or megaparsecs). For comparison, the Milky Way has a diameter of at least 26,800 parsecs (87,400 ly) and is separated from the Andromeda Galaxy, its nearest large neighbour, by just over 750,000 parsecs (2.5 million ly). (Full article...)

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Did you know - show different entries

... that 12th-century Muslim scientist Al-Khazini, who proposed a theory of gravitation long before Isaac Newton, was, in his early life, a slave of the Seljuq Turks?
... that Kepler-47c is a circumbinary planet orbiting in the habitable zone of Kepler-47, a binary star system?
... that two high school students used the automated telescope at Leuschner Observatory to record the earliest images of supernova SN 1994I?
... that the Kuiper crater in the Kuiper quadrangle, named after Dutch American astronomer Gerard Kuiper, has the highest albedo recorded on Mercury?
...that Mt. Olympus Mons on Mars is the highest peak in the solar system?

More Did you know facts

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... 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 Susan Murabana created Africa's first permanent planetarium?
... 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 star TRAPPIST-1 has seven planets, several of which may have temperatures that would allow the existence of liquid water (artist's impression depicted)?
... that Michael Collins has been called "one of the best clarinettists walking the planet" by The Times?

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WikiProjects

WikiProject Astronomy	WikiProject Solar System



WikiProject Cosmology	WikiProject Spaceflight

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Credit: Ken Crawford

NGC 4565 (also known as the Needle Galaxy or Caldwell 38) is an edge-on spiral galaxy about 30 to 50 million light-years away in the constellation Coma Berenices. The 10th magnitude galaxy sits perpendicular to our own Milky Way galaxy and is almost directly above the North Galactic Pole. First spotted in 1785 by Sir William Herschel (1738–1822), this is one of the most famous examples of an edge-on spiral galaxy.

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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