Question

Why do astronomers use astronomical units (AU) instead of kilometers (km)?(1 point)
Responses

There are no km in outer space, only AU.
There are no km in outer space, only AU.

AU is used for spacing, while km is used for length.
AU is used for spacing, while km is used for length.

Large distances are easier to express in AU than in km.
Large distances are easier to express in AU than in km.

AU is used in astronomy, while km is used in physics.

Answer 1

Large distances are easier to express in AU than in km.