A nanometer is a unit of length equal to one billionth of a meter (10^-9 m). It's used to measure very small things like atoms and molecules.

A light-year is the distance that light travels in one Earth year. It's a unit of astronomical distance, approximately 9.46 trillion kilometers or 5.88 trillion miles.

This conversion is usually for conceptual or educational purposes, to emphasize the vast difference in scale between microscopic objects and the distances in space.

100,000,000 nanometers is a very small distance (0.1 mm). Converting it to light-years results in an extremely tiny fraction (0.0000 ly) because a light-year is such a colossal distance.