# What is Light year, why we are using the term If you are hearing this term (Light year) first time, you will definitely think about the purpose of this word. Light year is nothing but the measurement which is gonna be used to measure the distance in space related subjects. suddenly your mind may ask a question, “If light year is used to measure the distance then why we didn’t use kilometre?”

Here we are going to see about the distance measuring unit….

## Light year

The travelling distance of light throughout the year will called as Light year.

As per the above definition, the value will be calculated as follows…

We know that Speed of light = 3*108 m/s

which means, light can travel 3*108 metre within a second

then light travelled distance within a minute = 60*3*108 metre

light travelled distance within an hour = 60*60*3*108 metre

light travelled distance within a day = 24*60*60*3*108 metre (Approx. a day is having 24 hours)

light travelled distance within a year = 365.25*24*60*60*3*108 metre (Approx. a year is having 365.25 days)

Then one light year’s value = 9 467 280 000 000 000 metre or 9.467*1015 metre (Approx.)

Now imagine yourself if you use this value each time to describe the distance between two planets then definitely you will get tired. So that, For ease of accessing the units and measurements we are using light year.

Once again keep in your mind, Light year is used to measure the distance not time.

Read this same info in Tamil