The planets have (their) moons. So the answer would be planets.
Answer: Because of the longitudinal motion of the air particles, there are regions in the air where the air particles are compressed together and other regions where the air particles are spread apart. These regions are known as compressions and rarefactions respectively
Explanation:
A moment causes a rotation about or axis. If the moment is to be taken about a point due to a force F, then in order for a moment to develop, the line of action cannot pass through that point...... the total moment was zero because the moment arm was zero as well