2007-09-24 02:26:44 · 10 answers · asked by Leekkul 1 in Science & Mathematics ➔ Astronomy & Space
It's a standard of measure
just like in miles,kilometers, gallons, liters. etc.
2007-09-24 02:36:06 · answer #1 · answered by Larry J 5 · 0⤊ 0⤋
There are three main units scientists use: First is the astronomical unit (AU), which is defined as the distance from the earth to the sun - 93 million miles, or 150 million kilometers. That's just for "local" measuring - for example, Mars is about 1.6 AU away. Next is the light year, which is the distance light travels in a year - about 6 trillion miles, or 9.5 trillion kilometers. The nearest star is about 4.3 light years away. Another unit, not as common as the first two, is the parsec. Parsecs were used to make some astronomical math easier, but in today's world of calculators and computers that excuse doesn't work any more, so parsecs aren't used much any more. The complicated definition is that a parsec is the paralax of one arc-second (hence the name PAR-SEC). The easy answer is that it's 3.26 light years, 19 trillion miles, or 30 trillion kilometers. I define it as a VERY long ways!
2016-05-17 09:08:33 · answer #2 · answered by ? 3 · 0⤊ 0⤋
See it is not practically possible to measure stellar distances. So we need to have an alternate method to estimate(Kindly note it is Just an Estimate) the inter stellar distances. The most accepted method is LY(Light YEar Concept)
light-year or lightyear (symbol: ly) is a unit of measurement of length, specifically the distance light travels in a vacuum in one year(Source Wikipedia)
Also there is myth that Light YEars cannot be translatd ot miles or any other units which is wrong please find the details of Light Year in different Units
A light-year is equal to:
9,460,730,472,580.8 km (about 9.461 Pm)
5,878,625,373,183.61 statute miles
about 63,240 astronomical units
about 0.3066 parsecs
2007-09-24 02:39:19 · answer #3 · answered by Alex 2 · 0⤊ 0⤋
It's because space is too big to be measured by anything smaller than lightyears.
2007-09-24 04:46:09 · answer #4 · answered by Pokorin 1 · 0⤊ 0⤋
The Universe is so large that we need a very big yardstick to measure it.
Light years are only good enough for our galaxy, for greater distances we use the "Parsec" The name parsec stands for "parallax of one second of arc", and one parsec is defined to be the distance from the Earth to a star that has a parallax of 1 arcsecond. The actual length of a parsec is approximately 3.086×1016 m, or about 3.262 light-years.
2007-09-24 02:35:10 · answer #5 · answered by Anonymous · 0⤊ 0⤋
It was just a matter of convention. The actual mathermatical measurement is really in term of paralax angle of measurement relative to the Earth.
Hence all atronomical measurements are relative to the Earth, including the speed of light. However that does not mean that the speed of light at the outskirt of the Universe is the same.
2007-09-24 02:43:25 · answer #6 · answered by goring 6 · 0⤊ 1⤋
Because miles are just too small for measuring such large distances. Which do you like better, Polaris is 430 light years away or 21,700,000,000,000,000 miles away? I mean really, that is just ridiculous. And I didn't just make that number up, that really is how many miles 430 light years is. Really.
2007-09-24 02:29:46 · answer #7 · answered by campbelp2002 7 · 0⤊ 0⤋
Because it is a constant speed/unit of measure. Light always travels at that speed. It also provides a sense of perspective on just how far something is.
Kent in SD
2007-09-24 02:31:37 · answer #8 · answered by duckgrabber 4 · 0⤊ 1⤋
Because there's no unit that's longer than lightyear.So we use it to measure long distances.
2007-09-24 02:36:13 · answer #9 · answered by kid 2 2 · 0⤊ 3⤋
because it sounds better then miles lol
2007-09-24 02:33:05 · answer #10 · answered by strongtack 2 · 0⤊ 1⤋