The astronomical unit (AU) is approximately how many kilometers?

The astronomical unit (AU) is approximately how many kilometers?

• A. 150 million kilometers
• B. 1 million kilometers
• C. 1 billion kilometers
• D. 15 million kilometers

Answer: (A)

An astronomical unit is the standard distance used to express distances within the solar system, defined as the average distance from the Earth to the Sun. That distance is about 149.6 million kilometers, so it’s commonly rounded to 150 million kilometers. This makes 150 million kilometers the closest approximate value for an AU. In context, distances inside our solar system are often described in AU to keep scale manageable. The other options are far off the solar-system scale: 1 million kilometers is much smaller than the Sun–Earth distance, 1 billion kilometers is larger than the typical orbital radius, and 15 million kilometers is also too small.

An astronomical unit is the standard distance used to express distances within the solar system, defined as the average distance from the Earth to the Sun. That distance is about 149.6 million kilometers, so it’s commonly rounded to 150 million kilometers. This makes 150 million kilometers the closest approximate value for an AU. In context, distances inside our solar system are often described in AU to keep scale manageable. The other options are far off the solar-system scale: 1 million kilometers is much smaller than the Sun–Earth distance, 1 billion kilometers is larger than the typical orbital radius, and 15 million kilometers is also too small.