Light Years

 

                                

 What is a Light Year                

How Far is a Light-Year?

A light year is a unit of length that astronomers use to measure the distance between stars. It is the distance light will travel in a year, especially in outer space. A light year is equivalent to 9,460,000,000,000 kms or 5,860,000,000,000 miles.

 

 How to calculate a light year:

The speed of light is 186,282 miles per second /299,793 km per second. This is known as a light second. Multiply this number by the total time a year takes to pass to get a light year.

Equation for calculating a light year:

186,282 miles/second X 60 seconds/minute X 60 minutes/hour X 24 hours/day X 365,25 days/ year = 5,878,612,843,200 miles (9,460,747,576,800 kilometres)

This is approximate to 5,880,000,000,000 miles or 9,460,000,000,000 kilometres (5,88 trillion miles or 9,46 trillion


How to calculate in terms of light years

When you want to express miles in terms of light years, divide the value you want to express by 5.88 trillion light years

-For example: If you wish to find out how many lights years is 20 trillion miles equivalent to, divide it by 5.88 trillion kilometres per light year. You will get 3.40 light years. (to the nearest 3 significant figures)

When you want to express kilometres in terms of light years, divide the value you want to express by 9.46 trillion kilometers.

-For example: If you wish to find out how many lights years is 94.6 trillion kilometres equivalent to, divide it by 9.46 trillion kilometres per light year. You will get 10 light years.

When you want to express metres in terms of light years, divide the value you want to express by 9.46 quadrillion kilometres.

- For example: If you wish to find out how many light years is 40 quadrillion metres equivalent to, divide it by 9.46 quadrillion kilometres per light year. You will get 4.23 light years (to the nearest 3 significant figures)

Applications of Light Years in Space:

Calculations in terms of Light seconds

A light second is 186,282 miles

Light years the Sun is from the Earth:

Fig 3.1   The Sun as shown

The Sun is 93 Million Miles away from the Earth. It is less than a light year because a light year is 5.88 million miles. We will use light seconds to calculate this instead. A light second is 186,282 miles, as mentioned earlier.

93,000,000 miles divided by 186,282 miles is equivalent to 499.24308306760717621670370728251 seconds. When this extremely long number is divided by 60, the answer is 8.3207180511267862702783951213751, which is approximate to 8.3 light minutes.

Hence it only takes approximately 8.3 light minutes to reach the Sun.

A light minute is 60 light seconds

One light minute = 186,282 X 60

= 11176920 miles

A light hour is 60 light minutes.

One light hour is 60 light minutes

One light hour= 11176920 X 60

= 670615200 miles

One light day is 24 light hours

One light day = 670615200 X 24

= 16094764800 miles