what is the value of 1 light years in kilometers.who invented it?
479589
no one invented it. it is how fast light travels in one year,186000x60x60x24x365=5865696000
40033
It is equal to about 3.26 light years. Parsec stands for "PARallax of one arc SECond". It is extensively used in measuring astronomical distances.\n\nIt is based on the method of trigonometric parallax, one of the most ancient and standard methods of determining stellar distances. The angle subtended at a star by the mean radius of the Earth's orbit, around the Sun, is called the parallax. The parsec is defined to be the distance from the Earth of a star that has a parallax of 1 arcsecond. Alternatively, the parsec is the distance at which two objects, separated by 1 astronomical unit, appear to be separated by an angle of 1 arcsecond.\n\nSee: http://en.wikipedia.org/wiki/Parsec
84961
1 kilometer = 0.6214 miles
402996
Light travels at 186,000 miles per second, or 300,000 kilometers per second.
974250
This page gives a very nice table listing who, when, how, how accurately the speed of light has been measured including the first time when Olaus Roemer did it in a really neat way 330 years ago!\n\nhttp://math.ucr.edu/home/baez/physics/Relativity/SpeedOfLight/measure_c.html
529612
It was first proposed by the Ancient Greeks, then expounded upon by Newton, then again by Einstein, and most recently by our friend Hawking.\n\nHere is what Einstein proposed:\n\nEinstein proposed that light was not a continuous wave, but consisted of localized particles. As Einstein wrote in the introduction to a March, 1905 paper, "According to the assumption to be contemplated here, when a light ray is spreading from a point, the energy is not distributed continuously over ever-increasing spaces, but consists of a finite number of energy quanta that are localized in points in space, move without dividing, and can be absorbed or generated only as a whole."\n\nHope that helps.
818301
It's the distance light travels in a year, ie about\n\n5,878,625,373,183.61 statute miles.\n\n(Based on a reference year of exactly 365.25 days (each of exactly 24 hours). This is the value recommended by the International Astronomical Union. It is not a universal standard.)
495659
The accurate speed of light is 299,792,458 m/s.
19452
"A light year is the distance light travels in one year: about 9.461 × 10^15 metres or about 5.879 × 10^12 miles."\n\nFor some context, it is 4.22 light years to Proxima Centauri, the nearest star outside the solar system.
139145
The earth is one AU from the sun.  One AU is 93 million miles.  The diameter of the solar system is 80 AU.  There are about 6 trillion miles in a light year.  The speed of light is 186,000 miles per second.\n\nPerforming the math.  The solar system has a diameter of .0012 light years.\n\nThe .0012 is derived from the following equeation - 93 million miles times 80AU divided by (186000 miles per second times (365 days times 24 hours times 60 minutes times sixty seconds).
295328
The distances between stars is quite large .The general convention of Kilometers or miles cannot be used due o the large numbers that we would have to deal with .\nLight is defined to have a constant speed of 299792458m/s . This number is precise to the last digit .The distance trvelled by light in a year can be found using this velocity\nthe distance would be 299792458*60*60*24*365= a large number suitable to denote lage distances \nwhen we say that the distance is 5000 ly we do not wait for light to complete the  journey .We determine distances using a different method and then use the above number to find th distance
618284
light travels fastest than anyone in the world\nhis speed=1,079,252,848.8  kilometres per hour
267068
a light year isn't a speed, it's a distance, that's like asking how fast is a mile.\n\na light year is 5,865,696,000,000 miles
162749
The light had to travel 14 billion years.  Earth travels much slowly.
474792
(m)\n\nThe speed of light in a vacuum is exactly 299,792,458 metres per second (or 1,079,252,848.8  km·h-1, which is approximately 186,282.397 miles per second, or 670,616,629.4 miles per hour). This value is denoted by the letter c, reputedly from the Latin celeritas, "speed", and also known as Einstein's constant. Note that this speed is a definition, not a measurement, since the fundamental SI unit of distance, the metre, has been defined since 1983 in terms of the speed of light—one metre is the distance light travels in a vacuum in 1/299,792,458 of a second. The speed of light through a transparent medium (that is, not in vacuum) is less than c; the ratio of c to this speed is called the refractive index of the medium.
344154
Scientists have defined the speed of light in a vacuum to be exactly 299,792,458 meters per second (about 186,000 miles per second).\n\nThis definition is possible because since 1983, scientists have known the distance light travels in one second more accurately than the definition of the standard meter. Therefore, in 1983, scientists defined the meter as 1/299,792,458, the distance light travels through a vacuum in one second. This precise measurement is the latest step in a long history of measurement, beginning in the early 1600s with an unsuccessful attempt by Italian scientist Galileo to measure the speed of lantern light from one hilltop to another.\nMicrosoft ® Encarta ® 2006. © 1993-2005 Microsoft
13174
Hi Writholeen, the only flaw in JayNick's answer is the accuracy part. As per the National Institute of Standards and Technology, the exact value of Speed of Light in vacuum is 299,792,458 m/s. By exact, I mean there is no uncertainity till the last digit. \n\nTo be precise, what we usually call the "speed of light" is really the speed of light in a vacuum (the absence of matter). In reality, the speed of light depends on the material that light moves through. Thus, for example, light moves slower in glass than in air, and in both cases the speed is less than in a vacuum. However, the density of matter between the stars is sufficiently low that the actual speed of light through most of interstellar space is essentially the speed it would have through a vacuum, so we don't make much error by ignoring the difference.\n\nTo make it easier for you to convert, here is the speed in alternative units :\n\n(1) 983,571,056.4304461 foot/second\n(2) 11,802,852,677.165352 inch/second\n(3) 1,079,252,848.8 kilometer/hour\n(4) 299,792.458 kilometer/second\n(5) 582,749,918.3585312 knot\n(6) 880,991.0899527 mach\n(7) 670,616,629.3843952 mile/hour (mph)\n\nThese values are accurate to the 7th digit of decimal. \n\n\nFlaw in JayNick's answer:\n\nThe speed of light in kilometres per second is 279,600 kilometres/sec. Even if you approximate the actual value , 299,792.458 kilometer/second by round off the last three digit, the value would have been 300,000 kilometers per second.