What is a Light Year?
Simple Definition – The distance traveled by light during a year in a vacuum is called a light-year.
Example – Suppose a star is 4 light-years away from the Earth, that it will take 4 years for the light of that star to reach the Earth. We are looking at the past of that star because the light we are seeing today came out of that star four years ago.
This means that the star we see today was like this four years ago. If that star ends, we will know after four years.
Speed of Light – 299 792 458 m/s ( 3 × 10^8 )
1 light Year in Kilometer
1 Light Year – 9,460,800,000,000 Km ( 9.46 trillion Kilometers )
1 light Year in Meters
1 light year – 9,460,730,472,580,800 m
“ly” for one light-year
“kly” for a kilo light-year ( 1000 light-years )
“Mly” for a mega light-year ( 1000,000 light-years )
“Gly” for a gigalight-year ( 1000,000,000 light-years )
Light years are a unit of distance measuring, such as meters, kilometers. Although often we measure distances in meters and kilometers when we talk about the distance between the Milky Way Galaxy and Andromeda Galaxy, the distance measuring unit changes there.
Due to the huge distance, we use the light-year unit to measure the distance between the Milky Way Galaxy and the Andromeda Galaxy.
What do 5 light-years mean?
This means light takes 5 years to cover a distance of 5 light-years.
How old is our universe?
13.8 billion years
What is one light-year?
Light takes one year to travel to cover a distance of one light-year.