Answer: kilometers

AnswerCrossword Clue
KILOMETERSLight year's nine trillion
KILOMETERSSixty-four of these equal about 40 miles
KILOMETERSConversion figure
kilometersKILOMETER, a thousand metres also KILOMETRE
kilometersA metric unit of measurement equal to 1,000 meters (approximately 0.62 miles)