The earth's changing distance from the sun Revolution, rotation, and the parallelism of the earth's axis as it orbits the sun Revolution, the tilt of the earth's axis, and parallelism of the earth's axis as earth orbits the sun The tilt of the earth's axis 13.
(it; orbits; the sun Revolution) (The earth's changing distance from the sun Revolution, rotation, and the parallelism of the earth's axis; orbits; The tilt of the earth's axis 13)
it The earth's changing distance from the sun Revolution, rotation, and the parallelism of the earth's axis
orbits orbits
the sun Revolution
The tilt of the earth's axis 13