ARTICLE ON "LIGHT YEAR" AS IN ASTRONOMY

What is a Light-year?
If anyone has seen any sci-fi flicks, they must have come across this term called as a “Light Year”. This basically is a measure of distance which astronomers use. A mistake people make is to take it as a unit of time. The light year is mostly used to express distances to stars and other objects which are present in space. The closest star to sun is roughly 25,000,000,000,000 kilometers away, you can’t really describe that distance using your normal measurements of distance like a kilometer or a mile. So to measure these long distances we use a light-year.

How the “Light-year” was formed
From its keyword “Light”, we know that the speed of light is 299,792,458 m/s. Therefore the unit Light-Year is telling us how fast Light could move in a year. When calculating the Light-year, the Julian calendar is used. There are 365.25 days in a Julian year.

Let’s convert it to second:
In hours, that’s 24hrs X 365.25 = 8766 hrs
In minutes, that’s 60 minutes X 8766 hrs = 525960 minutes
In seconds, that’s 60 seconds X 525960 = 31,557,600 seconds

This means there are 31,557,600 seconds in a Julian year. So a “Light-Year” is the distance it will take light to complete that amount of seconds. For example if my bicycle travels at the speed of light, it will have to complete approximately 32 million seconds to reach a Light-Year.

Still confusing? Let’s use this illustration. We all know it takes roughly 8 minutes for light to reach the Earth from the Sun, we could say that it takes 8 light-minutes for light to reach the Earth from the Sun


In calculation, a light-year = The speed of Light X Time it will travel in a year.
That is a light year = 299,792,458 m/s X 31,557,600 sec
A light year = 9,460,730,472,580,800 m or
In terms of miles: 5,878,625,373,183 miles

Another case study is the Proxima Centauri which is the closest star to the Sun is 4.24 light years away.
Since 1 light year = 5.878 X 10¹² miles
4.24 light years = 24,925,371,582,298 miles (24.93 X 10¹² miles)
Or 4.0 X 10¹⁶ (meters)


If you have any question to ask, feel free...


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