sentences: light years ly are an astronomy unit used for measuring length / distance generally used for values between 1 and 27000000000
docs: astronomy_unit is linear_unit. long_measure is linear_unit. light_minute is astronomy_unit. light_hour is astronomy_unit. light_year is measurement_of_distance_not_time. luminous_intensity_unit is light_unit. light_time is distance. light_second is astronomy_unit. length is distance. light_year is astronomy_unit.