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 the distance that light travels in a vacuum in one Julian year (365.25 days). It's a unit of astronomical distance.

This conversion is extremely small because a nanometer is infinitesimally tiny compared to the immense distance of a light-year. The result is practically zero.

While direct numerical conversion is possible, it's rarely practical due to the extreme difference in scale. These units are usually used to describe vastly different phenomena (microscopic vs. astronomical).