The Planets

Which planet is called red planet?

Which planet is known as the red planet?

What are inner planets and outer planets ? Name them .

Two planets have the same mass, M. Each planet has a constant density, but the density of planet 2 is twice as high as that of planet 1. Identical objects of mass m are placed on the surfaces of the planets. What is the relationship of the gravitational potential energy, U_(1) on planet 1 to U_(2) on planet 2?