Distances to objects in space are very, very large. The nearest star (excluding the Sun), Alpha Centauri, is 41.23 trillion km, or 41,320,000,000,000 km!!
Impact craters are made when a space rock (called a meteorite or asteroid) hits a rocky planet or moon. The impact makes a round hole in the surface, called a crater.
You have likely heard about the Universe expanding. Or that redshift can tell us about the movements of galaxies. Both are difficult ideas to imagine and understand.