What is the definition of a "light year" and what is the mathematical formula??
551177
If light travels 186,000 miles per second, then how far in 60 seconds (1 minute), how far in 60 minutes (1 hour), how far is that in 24 hours (1 day), how far is that in 365.25 days (one year, allowing for a leap year).  Crunch the numbers.
621324
Around 105 light years, or 3x10^5 km/s * 365 * 24 * 3600s * 105 km, or 993 384 000 000 000 km, or 617 277 076 989 996 mi
434263
The meaning of the equation is "energy equals mass times the speed of light (299,792,458 m/s) squared."
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
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
403997
Astronomy:The life of Stars. You can get some awesome pictures for that and there is plenty to write about, like (i am not completely sure about this number)did u know that light takes almost 250,000 years to travel from the center of our sun to the surface.\n\nhttp://en.wikipedia.org/wiki/Star
246225
Currently, the accepted view is that the universe is approximately 78 billion light-years in size. A light-year is the distance light travels in one year (a large number since light travels about 186,000 miles each second). To determine this, astronomers used the WMAP project. See the links to determine how this was accomplished, but only if you don't mind being confused (it is quite lengthy and quite confusing - even for an astronomer such as myself!).
344107
distance travlled by light in one year.\n\nso, mathematically, that is:\n\n299792458*365*24*3600\n\n= 9.45425496 × 10^15 metres
259168
Light travels at 670,616,629.4 miles per hour, so you multiply that by the number of hours in 35 years.\n\n35 years x 365 days/year x 24 hours/day x speed of light in miles/hour.\n\nIt's like 205,611,058,574,040 miles.
765526
As you know, light year is not a measure of time but the naswer is:\n\n365x24=8760
821198
persec is the largest unit of distance and is 3.26 times of a light year.Whereas one light year is equal to 9.45X10^12 km ,one persec is equal to 30.84X 10^12 km.This is the reason for using persec
647693
lots :-)  Let me figure it out...\n\nFirst the number is spelled 'googol' and is equal to 10^100 (1 followed by 100 zeroes).\n\nA year nominally has 31,556,926 seconds (365.242199 days x 24 hours x 60 minutes x 60 seconds).  I used the number 365.242199 because that is how long it takes for the earth to go once around the sun... we round this to 365 and add an additional day every 4 years (with some exceptions 3 out of every 4 centuries, blah, blah, blah)...\n\nAnyway, I digress.  Back to the problem at hand.\n\n10 x 10^99 / 3.1556926 x 10^7 = (10/3.1556926) x 10^92\n\n3.16887646 × 10^92 years.  There is no English name for this word but it is *lots* like I said at the beginning.  :-)\n\nThe closest I can get to a name would be to use vigintillion (10^63) as a base and go from there...\n\n3.16887646 x 10^29 x 10^63 or\n\n316 x 10^27 x 10^63 +\n887 x 10^24 x 10^63 +\n646 x 10^21 x 10^63\n\nSo that would be:\n316 octillion-vigintillion, 887 septillion-vigintillion, 646 sextillion-vigintillion years\n\nOkay, a little more research and I found that my names were close but not exactly correct.  This number should be called:\n  \n316 octovigintillion 887 septenvigintillion 646 sexvigintillion years!
537507
1 lightyear = 9.4605 × 10^15 meters\n70 miles/hr = 9.875*10^8 meters/year\n\n9.4605 × 10^15 meters/ 9.875*10^8 meters/year = 9.58*10^6 years
174626
Basically, it's the degree of brightness of a star.\n\nThe websites below might be able to help you with your question.
262422
Time is a measurement of movement through space. The earth rotates around the sun once = one year, the earth completing one spin on it's axis = one day, etc...\n\nFor measuring distances in space we use light years (the time it takes for light to go from point a to b) instead of miles because the distances are so great. Example: If we look at the closest star in the night sky, it's about 4 light years away. That means it's measured by how long that star's light takes to reach our eyes. So we are really looking at how the star looked 4 years ago, not now. If that star exploded 2 years ago, we would still see it for another 2 years and then we see it explode.
882266
Using Kepler's laws (third law):\n\nThe ratio between the T*T and a*a*a is a constant for our Sun and it applies to all objects rotating around it. where T is the period and a is the average distance. \nSo:\nT2=T1*(a2/a1)^(3/2) ;  ^ is used for power \nT2=1year *[  (4.5*10^9)  /  (1.5*10^9)  ]^(3/2)\nT2=164.3 years     \nTo make sure...see the links
45682
I love this question. The best way to do conversions is to simply type them into Google like this:\n\n25 light-years in miles\n\nWhich gives roughly 147 trillion miles. See how easy it is? This is a great Google tip.\n\nYou could enter this on your calculator as 147 EE 12\n\nIn metric 25 light-years is roughly 237 petameters (237 Pm) which is about the distance to the Star Fomalhaut in the constellation of the Southern Fish.\n\nBy comparison our Milky Way Galaxy is hundreds of billions of stars in a disc about 100,000 light-years across.