A light-year is a unit of distance, specifically the distance that light travels in one year.

50000 kilometers is equal to 0.0000 light-years, a very small fraction of a light-year.

Kilometers are too small to measure the vast distances in space, making light-years a much more practical unit.

While technically possible, light-years are generally too large for distances within our solar system. Astronomical Units (AU) are more commonly used.