The article discusses the prograde and retrograde motions of planets. Prograde is defined as the apparent eastward motion of a planet in the sky relative to the stars, while retrograde is the apparent westward motion of a planet. Topics discussed include the orbital speed of planets and how this impacts the way the planets appear to be moving, the slower orbital speed of outer planets including Mars, Jupiter, and Saturn, and the placement of the Sun and Earth on the March equinox.