Question

Why do scientists use it to explain distances in space?

Answer 1

I dont really know what you are asking. You should be more clear with your question. Do you mean light years, because that is what scientist use to measure distance in space. The reason that they use this system because the distace is so great and it is easier on the scientist. But they also use astronomic units for distances within our solar system, parsecs and megaparsecs to measure distances between stars, as well as distances on the galactical and inter-galactical scale, and redshift to measure extreme distances that are significant on cosmological scale.