Light-year
hideA light-year or light year (symbol: ly) is a unit of length, equal to just under 1013 kilometres. As defined by the International Astronomical Union (IAU), a light-year is the distance that light travels in a vacuum in one Julian year.
The light-year is often used to measure distances to stars and other distances on a galactic scale, especially in non-specialist and popular science publications. The preferred unit in astrometry is the parsec, because it can be more easily derived from, and compared with, observational data. The parsec is defined as the distance at which an object will appear to move one arcsecond of parallax when the observer moves one astronomical unit perpendicular to the line of sight to the observer, and is equal to approximately 3.26 light-years.
The related unit of the light-month, roughly one-twelfth of a light-year, is also used occasionally for approximate measures.
For more information about Light-year, read the full article at
Wikipedia.
This text uses material from Wikipedia and is available under the GNU Free Documentation License.
News tagged with light years
Rapid star formation spotted in 'stellar nurseries' of infant galaxies
Nov 11, 2009 |
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The Universe's infant galaxies enjoyed rapid growth spurts forming stars like our sun at a rate of up to 50 stars a year, according to scientists at Durham University.
Sea level stargazing: Astronomers make key sighting with Florida telescope
Sep 28, 2009 |
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(PhysOrg.com) -- This summer, University of Florida astronomers inaugurated the world's largest optical telescope on a nearly 8,000-foot mountaintop 3,480 miles away. But it was a far more modest observatory, located just ...
New INL project will improve nuclear reactor simulations
Sep 25, 2009 |
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A new project at Idaho National Laboratory and Brookhaven National Laboratory will improve the way scientists model the inner workings of nuclear reactors.
Research Team Discover New Tidal Debris from Colliding Galaxies
Jun 09, 2009 |
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Astronomers have discovered new tidal debris stripped away from colliding galaxies. The research will be being presented during a press conference at the 214th annual American Astronomical Society meeting ...
Three times farther away in outer space than previously possible -- a new way to measure cosmic distances
Jun 08, 2009 |
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Ohio State University researchers have found a way to measure distances to objects three times farther away in outer space than previously possible, by extending a common measurement technique.
Planet-Hunting Method Succeeds at Last
May 28, 2009 |
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(PhysOrg.com) -- A long-proposed tool for hunting planets has netted its first catch -- a Jupiter-like planet orbiting one of the smallest stars known.
Suzaku snaps first complete X-ray view of a galaxy cluster
May 28, 2009 |
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The joint Japan-U.S. Suzaku mission is providing new insight into how assemblages of thousands of galaxies pull themselves together. For the first time, Suzaku has detected X-ray-emitting gas at a cluster's ...
Better Supernovae Measurements Aim To Improve Understanding of Dark Energy
May 22, 2009 |
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(PhysOrg.com) -- A new technique for measuring the distances to supernovae more accurately than ever before has been developed by a team of scientists from Yale University, Lawrence Berkeley National Laboratory ...
Largest collection of anomalous white dwarfs observed by Hubble
Apr 23, 2009 |
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Twenty-four unusual stars, 18 of them newly discovered, have been observed in new Hubble telescope images. The stars are white dwarfs, a common type of dead star, but they are odd because they are made of ...
Mysterious space blob discovered at cosmic dawn (w/Video)
Apr 22, 2009 |
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(PhysOrg.com) -- A team of astronomers, led by Carnegie's Masami Ouchi, have discovered a mysterious, giant object that existed when the universe was only 800 million years old. Dubbed an extended "Lyman-Alpha ...
Astronomers find most crowded collision of galaxy clusters
Apr 16, 2009 |
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The most crowded collision of galaxy clusters has been identified by combining information from three different telescopes. This result gives scientists a chance to learn what happens when some of the largest ...
Scientists solve mystery of starlight's origins
Apr 08, 2009 |
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(PhysOrg.com) -- Scientists from the University of Toronto and the University of British Columbia have helped unveil the birthplaces of ancient stars using a two-tonne telescope carried by a balloon the size ...
Guide to galaxy for Earth Hour's starry, starry night
Space & Earth / Space Exploration
Mar 18, 2009 |
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(PhysOrg.com) -- When cities turn off their lights for Earth Hour their occupants will get more than a warm and fuzzy green feeling, they will also see stars hundreds of trillions kilometres away lighting up a moonless night ...
Drama in the heart of the Tarantula
Dec 11, 2008 |
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Found in the nearby Large Magellanic Cloud, 30 Doradus is one of the largest massive star forming regions close to the Milky Way. Enormous stars in 30 Doradus, also known as the Tarantula Nebula, are producing ...
