A light-year is the distance that light travels in a vacuum in one Earth year. It's a unit of astronomical distance.

There are approximately 5.88 trillion miles in one light-year.

No, 100,000 miles is a very small distance in the context of space. For comparison, it's a tiny fraction of a single light-year.

We convert miles to light-years to understand and compare distances on a cosmic scale, as distances in space are so vast that miles become impractical.