its energy
Gravity..
A circle but Pluto (which is not considered a planet currently) makes an oval shape.
The sun does because it's light reflects off the moon. The more light reflected the bigger the shape. The less light reflected, the smaller the shape.
The gravitational pull between the planets and the sun keep the planets orbiting the sun all day everyday.
The sun maintains its size and shape through a balance of forces. Gravity pulls inward, trying to collapse it, while nuclear fusion at its core generates energy that pushes outward. These two opposing forces create an equilibrium that sustains the sun's size and shape.
Gravity is the force that makes the Sun and planets roughly spherical in shape. Their rotation, if fast enough, will cause their equators to bulge and their poles to be somewhat flattened. The sphere is the perfect shape in nature for all fluids. Any body of fluid acted upon only by its own gravity will assume the shape of a sphere, where every point on the surface is equidistant from the center of gravity. Objects in the solar system are composed of gas, ice, and rock. If they are large enough, they reach "hydrostatic equilibrium" in which their matter is forced together by gravity into a spherical or ellipsoid shape.
Gravity is the force that makes the Sun and planets roughly spherical in shape. Their rotation, if fast enough, will cause their equators to bulge and their poles to be somewhat flattened. The sphere is the perfect shape in nature for all fluids. Any body of fluid acted upon only by its own gravity will assume the shape of a sphere, where every point on the surface is equidistant from the center of gravity. Objects in the solar system are composed of gas, ice, and rock. If they are large enough, they reach "hydrostatic equilibrium" in which their matter is forced together by gravity into a spherical or ellipsoid shape.
The shadow is caused by the earth blocking the path of the light from the sun casting shadow on the moon. When the earth is not in between the sun and the moon then we have a "full moon."
A planet's orbit around the sun is in the shape of an oval.
It has to keep its shape to do its particular job.
A solid shape with regular area and height makes a prism. A solid shape with regular area and height makes a prism. A solid shape with regular area and height makes a prism.
The Moon of the Earth has a spherical shape regardless to its position compared to the Sun.