What is constant is the rate at which the line joining the planet to the sun sweeps out the area lying between its orbit and the sun. A moving object will continue moving in a straight line at a constant speed, and a stationary object will remain at rest, unless acted on by an unbalanced force. For every action there is an equal and opposite reaction. In an isolates system, the total amount of energy, including heat energy, is conserved. You cannot construct an engine that does nothing but convert heat to useful work.
Every isolated system becomes more disordered with time.
The entropy of an isolated system remains constant or increases. Entropy is a measure of the disorder in a physical system. Galilo Galilei is considered to be the father of the scientific method. You should know the names of the planets in the solar system, and the order of their orbits from smallest, i.e. closest to the sun, to largest, i.e. furtherest from the sun. You should know that the inclination of the earths axis of rotation at 23 degrees from the plane of the earth's orbit around the sun is what produces 4 distinct seasons in most of North America.