A light-year is a unit of distance, representing the distance that light travels in one year in a vacuum. Since the speed of light is approximately 299,792,458 meters per second, we can calculate the distance traveled by light in one year as follows:
Distance = Speed of Light × Time
Distance = 299,792,458 meters/second × 1 year
To convert this distance into a more convenient unit for astronomical distances, we can use kilometers. There are approximately 9.461 × 10^12 kilometers in one light-year.
Distance = 299,792,458 meters/second × 60 seconds/minute × 60 minutes/hour × 24 hours/day × 365.25 days/year (accounting for leap years)
Distance ≈ 9.461 × 10^12 kilometers/year
Now, to find how many years correspond to a given distance in light-years, we can use the following formula:
Years = Distance (in light-years) / Distance (in kilometers per year)
Let's calculate how many years are in 20 light-years:
Years = 20 light-years / (9.461 × 10^12 kilometers/year)
Years ≈ 2.12 × 10^12 years
Therefore, 20 light-years is approximately equal to 2.12 trillion years.