One light-year is a unit of distance, representing the distance that light travels in one year. Light travels at a speed of approximately 299,792 kilometers per second in a vacuum. To calculate the number of kilometers in a light-year, we need to multiply the speed of light by the number of seconds in a year.
Number of seconds in a year: 1 year = 365.25 days (including leap years) 1 day = 24 hours 1 hour = 60 minutes 1 minute = 60 seconds
Therefore: 1 year = 365.25 days × 24 hours × 60 minutes × 60 seconds = 31,557,600 seconds (approximately)
Distance traveled by light in one year: 299,792 kilometers/second × 31,557,600 seconds = 9,460,730,472,580.8 kilometers (approximately)
Therefore, there are approximately 9.46 trillion kilometers in one light-year.