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.

1 million kilometers is approximately 0.0000 light-years. This is a very small fraction of a light-year.

Astronomers use light-years because the distances in space are incredibly vast, making kilometers impractical and the numbers very difficult to manage.

In the context of interstellar or intergalactic distances, 1 million kilometers is a very small distance. It's more relevant for distances within our solar system or for very specific scientific calculations.