Portal:Astronomy
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 -
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Sunset at the equinox from the prehistoric site of Pizzo Vento at Fondachelli Fantina, Sicily (from History of astronomy) -
Historical accuracy of atomic clocks from NIST. (from Theoretical astronomy) -
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Places like Paranal Observatory offer crystal clear skies for observing astronomical objects with or without instruments. (from Amateur astronomy) -
Calendrical functions of the Berlin Gold Hat c. 1000 BC (from History of astronomy) -
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The main platform at La Silla hosts a huge range of telescopes with which astronomers can explore the Universe. (from Observational astronomy) -
9th-century diagram of the positions of the seven planets on 18 March 816, from the Leiden Aratea (from History of astronomy) -
50 cm refracting telescope at Nice Observatory (from Observational astronomy) -
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An 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) -
Amateur astronomy groups are often involved in outreach to introduce astronomy to the general public (from Amateur astronomy) -
Overview of types of observational astronomy by observed wavelengths and their observability. (from Observational astronomy) -
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The Oort cloud, one of the most successful theoretical models about the Solar System (from Theoretical astronomy) -
The Hubble Space Telescope (from History of astronomy) -
Amateur astronomer recording observations of the sun. (from Amateur astronomy) -
A map of the southern celestial hemisphere, also by Bayer (from History of astronomy) -
The Crab Nebula as seen in various wavelengths (from Observational astronomy) -
An amateur astrophotography setup with an automated guide system connected to a laptop (from Observational astronomy) -
One 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) -
History of the Universe – gravitational waves are hypothesized to arise from cosmic inflation, a rapidly accelerated expansion just after the Big Bang (from Physical cosmology) -
An 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) -
Babylonian tablet in the British Museum recording Halley's Comet in 164 BC (from History of astronomy) -
Portrait 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) -
The 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) -
A map of the northern celestial hemisphere from Johann Bayer's 1661 edition of Uranometria, the first atlas to feature star charts covering the entire celestial sphere (from History of astronomy) -
The Nebra sky disk, Germany, 1800–1600 BC (from History of astronomy) -
ALMA is the world's most powerful telescope for studying the Universe at submillimeter and millimeter wavelengths. (from Observational astronomy) -
Arabic astrolabe from 1079 to 1080 AD (from History of astronomy) -
Comparison of CMB (Cosmic microwave background) results from satellites COBE, WMAP and Planck documenting a progress in 1989–2013 (from History of astronomy) -
Segment 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) -
A voting session is conducted in 2006 International Astronomical Union's general assembly for determining a new definition of a planet (from Astronomer) -
Artist 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) -
Ultra HD photography taken at La Silla Observatory (from Observational astronomy) -
Sir Patrick Moore was one of the world's leading popularisers of astronomy. (from Amateur astronomy) -
Map 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 -
Apollo 8 (December 21–27, 1968) was the first crewed spacecraft to leave Earth's gravitational sphere of influence, and the first human spaceflight to reach the Moon. The crew orbited the Moon ten times without landing and then returned to Earth. The three astronauts—Frank Borman, James Lovell, and William Anders—were the first humans to see and photograph the far side of the Moon and an Earthrise.
Apollo 8 launched on December 21, 1968, and was the second crewed spaceflight mission flown in the United States Apollo space program (the first, Apollo 7, stayed in Earth orbit). Apollo 8 was the third flight and the first crewed launch of the Saturn V rocket. It was the first human spaceflight from the Kennedy Space Center, adjacent to Cape Kennedy Air Force Station in Florida. (Full article...)
Did you know -
- ... that the asteroid 2011 XC2 missed the Earth by less than 1 lunar distance on 3 December 2011?
- ... that the mass-luminosity relation, first derived by Arthur Eddington in 1924, helps astronomers find the distances to binary star systems?
- ... that the planetary nebula Abell 39 is unusually spherical, yet its central star is offset from the center?
- ... that data from Mariner 10 led to the discovery of Mercury's magnetic field in 1974?
- ... that the Toronto Magnetic Observatory had to be moved as the University of Toronto's electric lighting was interfering with observations?
More Did you know (auto generated)
- ... 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 in early depictions of Uranus in fiction, the planet was portrayed as solid
- ... that the galaxy NGC 1700 has a rotating hot gas disk glowing in X-rays after merging with another galaxy three billion years ago?
- ... that Na drugą planetę, published in 1895 as one of the earliest Polish science-fiction novels, was later criticized by communist-era censors for its perceived "adoration for America"?
- ... that the Springfield Science Museum is home to the oldest operating projection planetarium in the United States?
WikiProjects
Selected image -
The five Moons of Pluto include Pluto's small satellite Hydra. Image is an artist's concept of the surface of Pluto, Hydra (center), Charon (right) and Nix (bright dot on left).
Astronomy News
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- The Vera C. Rubin Observatory in Chile releases the first light images from its new 8.4-meter (28 ft) telescope. (Scientific American)
July anniversaries
- 1 July 2004 – The Cassini spacecraft arrives at Saturn after entering orbit
- 4 July 1997 – Mars Pathfinder and its rover, Sojourner, land on Mars, with the latter becoming the first rover to successfully travel the planet
- 5 July 1687 – Sir Isaac Newton's Philosophiæ Naturalis Principia Mathematica, which formulated the laws of motion and universal gravitation and applied them to celestial bodes, is first published
- 13 July 2007 – Gran Telescopio Canarias undergoes first light, becoming the largest telescope in the world
- 20 July 1969 – As part of the Apollo 11 mission, Americans Neil Armstrong and Buzz Aldrin become the first men to walk on the Moon
- 20 July 1976 – Viking 1 becomes the first spacecraft to successfully land on Mars and perform its mission
- 26 July 1971 – Apollo 15 launches with Lunar Roving Vehicle payload
Space-related Portals
Astronomical events
All times UT unless otherwise specified. Portal:Astronomy/Events/July 2025
Topics
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Subcategories
Things you can do
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Wikibooks
These books may be in various stages of development. See also the related Science and Mathematics bookshelves.
- Astronomy
- GAT: A Glossary of Astronomical Terms
- Introduction to Astrophysics
- General relativity
- Observing the Sky from 30°S
- Observing the Sky from 40°N
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