* Speed of light: Light travels at approximately 299,792,458 meters per second.

* Distance in a year: There are 31,536,000 seconds in a year (365 days * 24 hours * 60 minutes * 60 seconds).

Calculation:

1. Distance in meters: 0.5 light years * 299,792,458 m/s * 31,536,000 s/year = 4.730 x 10^15 meters

2. Distance in kilometers: 4.730 x 10^15 meters / 1000 meters/kilometer = 4.730 x 10^12 kilometers

Therefore, 0.5 light years is approximately 4.730 trillion kilometers.