**Question**

**How many km are there in one light year?**

**9.46 × 10**^{15}**9.46 × 10**^{12}**9.46 × 10**^{9}**9.46 × 10**^{6}

**Answer**

9.46 × 10^{12}

**Explanation**

To convert from light years to kilometres, we can use the speed of light as a conversion factor. The speed of light is approximately 299,792.458 kilometres per second. Therefore, we can calculate the distance in kilometres that light travels in one year as follows:

1 light year = (299,792.458 km/s) × (60 s/min) × (60 min/hr) × (24 hr/day) × (365.25 days/year)

Simplifying this expression, we get:

1 light year ≈ 9.46 × 10^{12} km

Therefore, there are approximately 9.46 × 10^{12} kilometres in one light year.