A light-year is a unit of distance commonly used in astronomy. It is defined as the distance that light travels in one year in a vacuum. Since light travels at a finite speed, which is approximately 299,792,458 meters per second (or about 186,282 miles per second), it takes a significant amount of time for light to traverse vast distances in space.
To calculate the value of a light-year, we can use the speed of light and the number of seconds in a year. One year consists of approximately 31,557,600 seconds (365 days multiplied by 24 hours, multiplied by 60 minutes, multiplied by 60 seconds).
So, the distance traveled by light in one year is:
Distance = Speed of light × Time
Distance = 299,792,458 meters/second × 31,557,600 seconds
The result is approximately 9.46 trillion kilometers (or about 5.88 trillion miles). Therefore, when we say that a star is located, for example, 10 light-years away from Earth, it means that the light from that star takes 10 years to reach us. In other words, we are seeing the star as it appeared 10 years ago, since the light we observe now has been traveling for that duration before reaching our eyes or telescopes.