Portal:Astronomy

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Astronomy portal

Astronomy is a natural science that is the study of celestial objects (such as moons, planets, stars, nebulae, and galaxies), the physics, chemistry, and evolution of such objects, and phenomena that originate outside the atmosphere of Earth, including supernovae explosions, gamma ray bursts, and cosmic background radiation.

Astronomy is one of the oldest sciences. Prehistoric cultures have left astronomical artifacts such as the Egyptian monuments and Nubian monuments, and early civilizations such as the Babylonians, Greeks, Chinese, Indians, Iranians and Maya performed methodical observations of the night sky. However, the invention of the telescope was required before astronomy was able to develop into a modern science. Historically, astronomy has included disciplines as diverse as astrometry, celestial navigation, observational astronomy, and the making of calendars, but professional astronomy is nowadays often considered to be synonymous with astrophysics.

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Selected article

Triton is the largest moon of the planet Neptune, discovered on October 10, 1846 by William Lassell. It is the only large moon in the Solar System with a retrograde orbit, which is an orbit in the opposite direction to its planet's rotation. At 2700 km in diameter, it is the seventh-largest moon in the Solar System. Because of its retrograde orbit and composition similar to Pluto's, Triton is thought to have been captured from the Kuiper belt. Triton consists of a crust of frozen nitrogen over an icy mantle believed to cover a substantial core of rock and metal. The core makes up two-thirds of its total mass. Triton has a mean density of 2.061 g/cm³ and is composed of approximately 15–35% water ice.

Triton is one of the few moons in the Solar System known to be geologically active. As a consequence, its surface is relatively young, with a complex geological history revealed in intricate and mysterious cryovolcanic and tectonic terrains. Part of its crust is dotted with geysers believed to erupt nitrogen.

The moon was discovered by British astronomer William Lassell just 17 days after Neptune itself was discovered by German astronomers Johann Gottfried Galle and Heinrich Louis d'Arrest, who were following co-ordinates given them by French astronomer and mathematician Urbain Le Verrier.

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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?

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Categories

Astronomy : Archaeoastronomy - Astrophysics - Calendars - Catalogues - Celestial coordinate system - Celestial mechanics - Cosmology - Images - Large-scale structure of the cosmos - Observatories - Planetary science - Telescopes - Universe

Biographies : Astronomers - Other people - Amateur Astronomers

Astronomical objects : Lists - Galaxies - Nebulae - Planets - Stars

Spaceflight : Human spaceflight - Satellites - SETI - Spacecraft

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Projects

WikiProject Astronomy	WikiProject Solar System
WikiProject Cosmology	WikiProject Spaceflight

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Space-related Portals

Star	Spaceflight	Moon
Space	Solar System	Mars
X-ray astronomy	Cosmology	Jupiter

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Selected picture

In astronomy, the Pleiades, or Seven Sisters (Messier object 45), is an open star cluster containing middle-aged hot B-type stars located in the constellation of Taurus. It is among the nearest star clusters to Earth and is the cluster most obvious to the naked eye in the night sky.

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January anniversaries

• 1 January 1925 – Astronomer Edwin Hubble formally presents his discovery of galaxies outside the Milky Way at a meeting of the American Astronomical Society
• 3 January 1888 – The 91-centimeter refracting telescope at Lick Observatory, the world's largest telescope from 1888 to 1897, sees its first light
• 4 January 2004 – The Mars rover Spirit lands, three weeks ahead of twin rover Opportunity, and begins exploring the Red Planet
• 14 January 2005 – The probe Huygens lands on Titan, a moon of Saturn, in the first successful landing in the outer Solar System
• 26 January 1949 – Hale telescope, which introduced several innovations to telescope construction and was the world's largest telescope for nearly 30 years, has its first light

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Things you can do

Here are some Open Tasks : Copyedit: Roque de los Muchachos Observatory, Europa (moon) More... Wikify: More... Merge: More... Requests: Borde-Vilenkin-Guth Theorem, Antigalaxy, Sunspot index, undefined names in the List of astronomers, More... Stubs: D Ring, Diffraction spike More... Discuss deletion: No deletion requests Astronomy featured article candidates: No current candidates Astronomy articles for which peer review has been requested: Epsilon Eridani (entry) Jupiter Trojan (entry)

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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

Wikijunior

• Solar System

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Astronomical events

All times UT unless otherwise specified.

3 January, 04:13	Moon occults Neptune
3 January, 06:46	Moon occults Mars
3 January, 14:00	Quadrantids peak
4 January, 14:17	Earth at perihelion
6 January	Comet 45P/Honda–Mrkos–Pajdušáková at max brightness
7 January	Pluto at conjunction
10 January, 06:09	Moon at perigee
12 January, 11:34	Full moon
12 January, 13:18	Venus at greatest eastern elongation
19 January, 09:42	Mercury at greatest western elongation
22 January, 00:17	Moon at apogee
28 January, 00:07	New moon
30 January, 11:25	Moon occults Neptune

Celestial events by month

Portals : Astronomy and Space

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