In astronomy planets and stars orbit around each other based on what

Plz ! ive been stuck on this forever

Amale bird-of-paradise uses a dance to attract mates in which it flaps its tail feathers on the ground and jumps around a potential female mate. a different male bird-of-paradise does a similar dance but it jumps around the female in the opposite direction. the female bird is only attracted to one style of dance, in one direction.

How does secondary succession differ from primary succession?