One astronomical unit is approximately how many kilometers?

• A. 150,000 km
• B. 150,000,000 km
• C. 1,500,000,000 km
• D. 15,000 km

Answer: (B)

Distances in the solar system are often expressed in astronomical units to compare how far other objects are from the Sun relative to Earth’s orbit. One astronomical unit is the average distance from Earth to the Sun, which is about 149.6 million kilometers. Rounded for ease, that’s roughly 150 million kilometers.

So the best answer is approximately 150,000,000 kilometers. The other numbers are far from the actual Earth–Sun distance: a few tens of thousands of kilometers is on the scale of Earth’s diameter or the Moon’s distance, and a distance around 1.5 billion kilometers would place you far beyond the outer planets.