The distance that light can travel in one year is known as a light-year. To understand this concept, it’s important to know how fast light travels. In a vacuum, light moves at an incredible speed of approximately 299,792 kilometers per second (or about 186,282 miles per second).
To calculate how far light travels in one year, you can multiply the speed of light by the number of seconds in a year. There are 60 seconds in a minute, 60 minutes in an hour, 24 hours in a day, and about 365.25 days in a year (accounting for leap years). Doing the math:
- Seconds in a year = 60 seconds/minute * 60 minutes/hour * 24 hours/day * 365.25 days/year
- Seconds in a year ≈ 31,557,600 seconds
Now, if we multiply the speed of light by the number of seconds in a year:
- Distance = speed of light * time
- Distance = 299,792 km/s * 31,557,600 seconds ≈ 9.461 trillion kilometers
This means that in one year, light travels approximately 9.461 trillion kilometers, or about 5.879 trillion miles. Therefore, when astronomers say something is a certain number of light-years away, they are referring to the vast distances that light can cover in one year, serving as an essential measure in the realm of astronomy.