2006-10-18 05:48:42 · 22 answers · asked by Anonymous in Education & Reference ➔ Homework Help
The distance that light can travel in one year.
2006-10-18 05:49:49 · answer #1 · answered by SoccerClipCincy 7 · 2⤊ 0⤋
A light year is a way of measuring distance. That doesn't make much sense because "light year" contains the word "year," which is normally a unit of time. Even so, light years measure distance.
You are used to measuring distances in either inches/feet/miles or centimeters/meters/kilometers, depending on where you live. You know how long a foot or a meter is -- you are comfortable with these units because you use them every day. Same thing with miles and kilometers -- these are nice, human increments of distance.
When astronomers use their telescopes to look at stars, things are different. The distances are gigantic. For example, the closest star to Earth (besides our sun) is something like 24,000,000,000,000 miles (38,000,000,000,000 kilometers) away. That's the closest star. There are stars that are billions of times farther away than that. When you start talking about those kinds of distances, a mile or kilometer just isn't a practical unit to use because the numbers get too big. No one wants to write or talk about numbers that have 20 digits in them!
So to measure really long distances, people use a unit called a light year. Light travels at 186,000 miles per second (300,000 kilometers per second). Therefore, a light second is 186,000 miles (300,000 kilometers). A light year is the distance that light can travel in a year, or:
186,000 miles/second * 60 seconds/minute * 60 minutes/hour * 24 hours/day * 365 days/year = 5,865,696,000,000 miles/year
A light year is 5,865,696,000,000 miles (9,460,800,000,000 kilometers). That's a long way!
Cool Fact
A light nanosecond -- the distance light can travel in a billionth of a second -- is about 1 foot (about 30 cm). Radar uses this fact to measure how far away something like an airplane is. A radar antenna sends out a short radio pulse and then waits for it to echo off an airplane or other target. While it's waiting, it counts the number of nanoseconds that pass. Radio waves travel at the speed of light, so the number of nanoseconds divided by 2 tells the radar unit how far away the object is!
Using a light year as a distance measurement has another advantage -- it helps you determine age. Let's say that a star is 1 million light years away. The light from that star has traveled at the speed of light to reach us. Therefore, it has taken the star's light 1 million years to get here, and the light we are seeing was created 1 million years ago. So the star we are seeing is really how the star looked a million years ago, not how it looks today. In the same way, our sun is 8 or so light minutes away. If the sun were to suddenly explode right now, we wouldn't know about it for eight minutes because that is how long it would take for the light of the explosion to get here.
2006-10-18 05:50:46 · answer #2 · answered by falsman14 2 · 0⤊ 0⤋
It's the distance that light will travel in a regular calender year. The way to figure the distance in regular land miles, is to take the speed of light 18,000 miles per second. Now take the 18,000 and multiply by 60, that gives you miles per minute, There are 60 minutes in an hour, so times the last figure by 60. Okay, that's a light day. To get the light year, multiply the light day figure by 365 ( days in a year ). So there's your light year.
If you plan on walking the distance, take some adhesive tape to pad the blisters on your feet.
2006-10-18 06:00:57 · answer #3 · answered by Anonymous · 0⤊ 0⤋
The distance that light travels in 1 year.
2006-10-18 05:50:13 · answer #4 · answered by Anonymous · 0⤊ 0⤋
A light-year or lightyear, symbol ly, is the distance light travels in vacuum in one Julian year.
A light-year is approximately equal to
9,460,528,404,879 km (about 9.461 Pm)
5,878,482,164,161 statute miles[1]
63,239.7263 AU (about 63,240 AU)
0.306601394 pc
The actual, exact length of the light-year depends on the length of the reference year used in the calculation, and there is no wide consensus on the reference to be used. The figures above are based on a reference year of 31,556,925.9747 seconds, but other reference years are often used, such that the light-year is not an appropriate unit to use when extremely high precision is required.
2006-10-18 05:50:11 · answer #5 · answered by Corn_Flake 6 · 1⤊ 0⤋
It's a measurement of distance like a mile or kilometer. A light year is the distance that light is able to travel in a year. As you can imagine, it's a very very large number of miles.
2006-10-18 05:51:25 · answer #6 · answered by Anonymous · 0⤊ 0⤋
A light year is a unit of distance equal to the distance that light travels in the vacuum of space in one mean solar year which is approx. 5.88 trillion miles. It can also mean a very long way in time, distance or some other quantity or quality.
from the Encarta dictionary
2006-10-18 05:56:34 · answer #7 · answered by Coo coo achoo 6 · 0⤊ 0⤋
The distance covered by the light in vacuum in one year is called light year.The distance is used for measurement of distance of the stars. 1 light year= 9.467 X 10^12 km(appox)
2006-10-18 05:55:51 · answer #8 · answered by alpha 7 · 0⤊ 0⤋
This term is complicated as a 'mild year' is a diploma of DISTANCE, no longer of time. a mild year is the area mild can return and forth in a year, it is 9.4605284 × 10^15 metres, or approximately 10 trillion kilometres.
2016-12-26 22:29:32 · answer #9 · answered by ? 3 · 0⤊ 0⤋
A light year is a year that felt so short as if it were a beam of light shooting past you.
Real Answer:
The distance that light can travel in one year in a vacuum. It is approximately 5.88 trillion miles
2006-10-18 05:51:44 · answer #10 · answered by Vim of the Vine 2 · 0⤊ 0⤋