My granddaughter ask me why are planets round,and other space objects are not (asteroids etc)?

Why is a bubble round? Spheres are the most efficient objects in the universe. In space, if one releases water, it's gravity will cause a spherical shape. Asteroids are the results of planets that have come apart due to different reasons, such as a core destabilization for instance. Chance however is not how the planets came to be, as all the objects in the universe show a sign of something other than chance. Earth at one time was a near perfect sphere, then something happened which caused the Earth to burst out from one area and turn the moon's face into the sea of tranquility you see today. Due to the type of the shot that occurred, the force that hit the moon had to be tens of billions of nuclear warheads of pressure to get that far and do that much damage. Since the moon's face always faces Earth an asteroid colliding with it is highly impossible because it would have had to swerve straight from earth to hit it where the damage is. The moon's surface does not turn, but it does move away from Earth, and that would be a reason why.