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

Titan (/ˈtaɪtən/, or as Ancient Greek: Τῑτάν), or Saturn VI, is the largest moon of Saturn, the only natural satellite known to have a dense atmosphere, and the only object other than Earth for which clear evidence of stable bodies of surface liquid has been found.

Titan is the sixth ellipsoidal moon from Saturn. Frequently described as a planet-like moon, Titan has a diameter roughly 50% larger than Earth's moon and is 80% more massive. It is the second-largest moon in the Solar System, after Jupiter's moon Ganymede, and it is larger by volume than the smallest planet, Mercury, although only half as massive. Titan was the first known moon of Saturn, discovered in 1655 by the Dutch astronomer Christiaan Huygens.

Titan is primarily composed of water ice and rocky material. Much as with Venus until the Space Age, the dense, opaque atmosphere prevented understanding of Titan's surface until new information accumulated with the arrival of the Cassini–Huygens mission in 2004, including the discovery of liquid hydrocarbon lakes in the satellite's polar regions. These are the only large, stable bodies of surface liquid known to exist anywhere other than Earth. The surface is geologically young; although mountains and several possible cryovolcanoes have been discovered, it is smooth and few impact craters have been discovered.

The atmosphere of Titan is largely composed of nitrogen, and its climate includes methane and ethane clouds. The climate—including wind and rain—creates surface features that are similar to those on Earth, such as sand dunes and shorelines, and, like Earth, is dominated by seasonal weather patterns. With its liquids (both surface and subsurface) and robust nitrogen atmosphere, Titan is viewed as analogous to the early Earth, although at a much lower temperature. The satellite has thus been cited as a possible host for microbial extraterrestrial life or, at least, as a prebiotic environment rich in complex organic chemistry. Researchers have suggested a possible underground liquid ocean might serve as a biotic environment.

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Did you know

• ... that although color-blind, Nicholas U. Mayall was better able to detect faint galaxies than most other astronomers?
• ... that The Man in the Moone, a 1638 book by the English bishop Francis Godwin, is considered one of the first science fiction books?
• ... that the galaxy Markarian 501 produces very high energy gamma rays?
• ... that the Near-Earth object and Mars-crosser asteroid 2007 WD5 is estimated to have a 1-in-75 chance of colliding with Mars?
• ... that hydroxyl megamasers were used to make the first detection of Zeeman splitting in a galaxy other than the Milky Way?

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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

Cassiopeia A (Cas A) is a supernova remnant in the constellation Cassiopeia and the brightest astronomical radio source in the sky, with a flux of 2720 Jy at 1 GHz. The supernova occurred approximately 11,000 light-years (3.4 kpc) away in the Milky Way.

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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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