Question

Which of the following measurements is used to measure the distance between astronomical bodies?

Speed of light
Speed of sound
Speed of spacecraft
Speed of rotation of Earth

Answer 1

combination of the orbit of the earth and the speed of light.
distances are measured in light years.

Answer 2

Generally we use speed of light to measure the distance between two astronomical bodies

Because astronomical bodies are very far from each other

and we use light year as the unit of distance for large distances

1 light year is the distance covered by light in one year

so speed of light is correct option here