Surely you'd use the base unit of time, the second (lightseconds)? atto-lightyear = 1e-18 lightyear lightyear = 3.156e+7 lightsecond Hence, atto-lightyear =

Surely you'd use the base unit of time, the second (lightseconds)? atto-lightyear = 1e-18 lightyear lightyear = 3.156e+7 lightsecond Hence, atto-lightyear = 3.156e-11 lightsecond = 31.56 pico-lightsecond