'Light-year' is a unit of
- Atime
- Bspeed
- Cdistance
- Dintensity of light
- ENone of the above / More than one of the above
Show answer and explanation
Correct answer: (c) distance
Explanation
A light-year is the distance travelled by light in vacuum in one Julian year, so it measures length, not time.
It equals about 9.46 × 10¹² km (≈ 6 trillion miles), using the speed of light 3 × 10⁸ m s⁻¹.
Other astronomical distance units are the astronomical unit (AU) and the parsec (pc).