Portal:Astronomy
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Astronomy portal
Astronomy (Greek: αστρονομία = άστρον + νόμος, astronomia = astron + nomos, literally "law of the stars") is the study of the evolution and physical and chemical properties of celestial objects. Astronomical observations are not only relevant for astronomy as such, but provide essential information for the verification of fundamental theories in physics, such as the general relativity theory. Complementary to observational astronomy, theoretical astrophysics seeks to explain astronomical phenomena.
Article of the month
Herbig–Haro objects are small patches of nebulosity associated with newly born stars, and are formed when gas ejected by young stars collides with clouds of gas and dust nearby at speeds of several hundred kilometres per second. Herbig–Haro objects are ubiquitous in star-forming regions, and several are often seen around a single star, aligned along its rotational axis.
HH objects are transient phenomena, lasting only a few thousand years at most. They can evolve visibly over quite short timescales as they move rapidly away from their parent star into the gas clouds in interstellar space (the interstellar medium or ISM). Hubble Space Telescope observations reveal complex evolution of HH objects over a few years, as parts of them fade while others brighten as they collide with clumpy material in the interstellar medium.
The objects were first observed in the late 19th century by Sherburne Wesley Burnham, but were not recognised as being a distinct type of emission nebula until the 1940s. The first astronomers to study them in detail were George Herbig and Guillermo Haro, after whom they have been named. Herbig and Haro were working independently on studies of star formation when they first analysed Herbig–Haro objects, and recognised that they were a by-product of the star formation process.
Recently featured: Big Bang – Main sequence – Zhang Heng
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Did you know
... that William Herschel's 40-foot telescope (pictured) was the largest telescope in the world for 50 years?
...that Zeeman-Doppler imaging is a technique used to map the surface magnetic field of stars?
...that Astronomische Nachrichten, founded by H. C. Schumacher in 1821, is the world's oldest existant astronomical journal?
...that the Stingray Nebula, thought to have formed around 1987, is the youngest known planetary nebula?
...that the Mark II radio telescope built in 1964 at Jodrell Bank Observatory, UK was the first ever telescope to be controlled by a digital computer?
...that Comet Shoemaker-Levy 9 passed within Jupiter's Roche limit in 1992, causing it to break up into smaller pieces two years before it collided with the planet?
...that the Kaidun meteorite fell on March 12, 1980 on a Soviet military base in Yemen and may be from Phobos?
Categories
Astronomy : Archaeoastronomy - Astrophysics - Calendars - Catalogues - Celestial coordinate system - Celestial mechanics - Cosmology - Images - Large-scale structure of the cosmos - Observatories - Planetary science - Telescopes
Biographies : Astronomers - Other people
Astronomical objects : Lists - Galaxies - Nebulae - Planets - Stars
Space exploration : Human spaceflight - Satellites - SETI - Spacecraft
Projects
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| Space | Solar System | Mars |
Picture of the week
NGC 1427A is an irregular galaxy in the constellation Eridanus.
Astronomy News
- October 18, 2009: IBEX satellite releases first all sky map
- October 7, 2009: New ring discovered around Saturn, could explain dark side of its moon
- September 27, 2009: Indian lunar mission Chandrayaan finds water on moon
- September 22, 2009: Images show new dimension to Saturn's rings
- August 27, 2009: Extrasolar planet will most probably fall into its star
- July 21, 2009: Black spot on Jupiter is impact site, says NASA
- June 25, 2009: Saturn moon may contain liquid water
- April 23, 2009: Gamma-ray burst, dubbed GRB 090423, was detected by Swift satellite
- January 16, 2009: International Year of Astronomy is launched
Astronomical events in December 2009
All times UT unless otherwise specified.
| 2 December, 07:32 | Full moon |
| 4 December, 14:00 | Moon at perigee |
| 14 December | Geminids peak |
| 16 December, 12:03 | New moon |
| 18 December, 17:00 | Mercury at greatest eastern elongation |
| 20 December, 15:00 | Moon at apogee |
| 21 December, 17:48 | Earth southern solstice |
| 22 December | Ursids peak |
| 31 December, 19:23 | Full moon and partial lunar eclipse |
Things you can do
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Here are some Open Tasks :
Astronomy featured article candidates:
Astronomy articles for which peer review has been requested: |
Wikibooks
These books may be in various stages of development. See also the related Science and Mathematics bookshelves.
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