The distance that light travels in one year is called a light-year. It is a unit of astronomical distance, representing the vast distances covered by light in the vacuum of space. One light-year is approximately 5.88 trillion miles (9.46 trillion kilometers). This measurement helps astronomers gauge the immense scale of the universe, allowing them to express distances to stars and galaxies in a more comprehensible way. For example, the nearest star system, Alpha Centauri, is about 4.37 light-years away, which illustrates the vastness of distances in the cosmos.