A light-year is the distance light travels in a vacuum in one Julian year (365.25 days). It's approximately 9.461 trillion kilometers or 5.879 trillion miles.

A nanometer (nm) is a unit of length in the metric system equal to one billionth of a meter (1 x 10^-9 m).

While rarely done in practice due to the immense scale difference, this conversion helps to conceptually grasp the vastness of space by expressing astronomical distances in an extremely small unit.

10 light-years is equal to 9.461e+25 nanometers. This is a massive number, emphasizing the enormous scale of a light-year.