One light- year is the distance light travels in one year. The speed of light is about 300,000 km/s (3 × 105 km/s). How far is 1 light- year?
A)18 million km (18,000,000, or 1.8 × 107 km)
B)9)46 trillion km (9,460,000,000,000, or 9.46 × 1012 km)
C)1)08 billion km (1,080,000,000, or 1.08 × 109 km)
D)300 thousand km (300,000, or 3 × 105 km)

Question

Quizplus · Accepted Answer

One light-year is the distance that light can travel in one year at its constant speed. The speed of light is about 300,000 km/s, and there are about 31,536,000 seconds in one year. Therefore, the distance that light can travel in one year is:
300,000 km/s x 31,536,000 s = 9,460,800,000,000 km 
or
9.46 x 10^12 km.
The closest answer choice is B, which is 9.46 trillion km.

One Light- Year Is the Distance Light Travels in One