A nanometer (nm) is a unit of length equal to one billionth of a meter. It's commonly used to measure atomic and molecular scales.

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

Because a light-year is an enormous distance, and a nanometer is an infinitesimally small distance, making the conversion result extremely close to zero.

While not a direct practical calculation for everyday tasks, it's useful for understanding and illustrating the immense differences in scale used in science, particularly in astrophysics and nanotechnology education.