Why are light year used to measure distance in outer space?

Answer 1

A lightyear is the distance light travels in a year, which is equal to just under 10 trillion kilometres. They use it just because its a lot easier to use. Its like trying to measure the distance from Canada to Mexico in centimetres. It's easier to use km, just like in space, where everything is so far apart, its easier to use lightyears.

Answer 2

meters, feet, and even miles are way too small to measure distances in space. astronomical units are mostly used to measure distances in our solar system. light years are used to measure the distances of things further away from our solar system.

Answer 3

Actually, light-years is a very common measurement across nonscientific disciplines, but scientists usually use a different measurement. The parsec, equal to 3.262 light-years, is the preferred method of measuring distances across space.

The parsec is defined as the distance at which an object's parallax will reach a maximum of one arc second as the Earth revolves around the Sun. Since the Earth is millions of miles away on the other side of its orbit (half a year from any given moment), it gives us a different viewing angle of an object. Similar to how if you close one eye, look at your thumb, and then switch eyes, your thumb appears to jump next to the background. If an object jumps one arc second in comparison to the distant background, then it is one parsec away.

There are also kiloparsecs (1000 parsecs), etc.

Answer 4

Professional astronomers usually prefer the "parsec", which is equal to about 3.26 light-years. In both cases, these units are used because of the vast distances in the Universe - using parsecs (or light-years), the distance to the nearest star, or galaxy, can be expressed without requiring scientific notation.

Answer 5

Light is the fastest thing we know of in the universe (so far!). Because other stars are so incredibly far away, it is convenient to measure the distance to other stars in "light-years"; the distance that light would travel in one year.

Light travels at 186,000 miles per SECOND, to a light year would be 186,000 miles per second * 60 seconds/minute * 60 minutes/hour * 24 hours/day *365.25 days per year = 5,869,713,600,000 miles. 5.8 TRILLION miles!

So measuring distances in light years means that we don't have to keep track of such big numbers.

Answer 6

There are different methods of calculating the distance to a celestial object. The method used depends on what the object is.

One common method is to use 'standard candles'. These are objects that have a known absolute brightness (we know how bright they are without factoring in distance. By measuring the apparent brightness, (how bright it looks to use form Earth), we can calculate the distance to that object. (Using the equation , where M is absolute magnitude, m is apparent magnitude, and DL is the distance is parsecs. [1 parsec is about 3.261563777 light years].)

Some standard candles are to use variable stars. They pulse in brightness, and we can figure out how bright they are by how fast the pulse.

Type Ia supernova can also be used as standard candles. They pulse, but there brightest phase is around the same magnitude for each type Ia supernova. We can use the peak brightness as seen from Earth to calculate the distance.

Answer 7

The light-year is used to describe the distance light travels in one Earth year. It's much easier to say 1 light-year than 9.5 million million kilometers. Often the term "parsec" is used as well. It is the equivalent to 3.3 light-years.

Answer 8

Light years are used to describe distance in space because light moves so fast. And the distance to other stars would look ridiculously long in miles. So here is an example to give you an idea.

Light moves at 186,000 miles per second. Our nearest star to our solar system is 4 light years away. Let's use math to work that out into miles.

If light travels at 186,000 miles per second, then it travels 11,160,000 miles per minute. Multiply that by number of minutes in an hour and you have 669,600,000 miles per hour. Multiply that by the 24 hours that make up a day and we have 16,070,400,000 miles per day. Now lets turn that into miles per year by multiplying our last number by 365. We now have 5,865,696,000,000 miles per year. We are already into trillions of miles per year, let's multiply that by the 4 years it would take for that light to reach our nearest star. 23,462,784,000,000. Yes that's 23.4 trillion miles that light will travel in 4 years.

Now, which is easier to say, "Twenty-three trillion, four hundred sixty-two billion, seven hundred eighty-four million miles" or "4 light years"?

To give you even more to chew on, astronomers have discovered what they believe to be an earth-like planet orbiting a star 20 light years away. Using the same math as before, that planet is 117,313,920,000,000 miles away. 117.3 trillion miles.

Answer 9

a lightyear is the distance light travels within a year and because the speed of light is always the same (within a vacuum wich space is) and that currently the speed of light is the fastest possible speed to travel it.

We therefore measure distances with this because we know that if we one day harness the speed of light, we know that it will take that many years to go there.

Answer 10

They use light years because it is a convenient measurement. You get more manageable figures that way. The star Alpha Centauri (which is a close neighbor of ours in the galaxy) is about four and a half light years away. It could also be described as 31 and a half trillion miles away.

To explain it further: If you measure something that is about the size of your hand, you use a measurement standard that is close to that size. The inch and the foot measurements started out as an inch meant a thumb and a foot was literally a foot long. So if you want to measure something that is so large that it requires light to travel long distances in both time and space, then the only convenient measurement 'yardstick' is to base it upon the speed of light, the fastest thing in the universe that travels the greatest distances!