The North Magnetic Pole is the point on the surface of Earth's Northern Hemisphere at which the planet's magnetic field points vertically downwards (in other words, if a magnetic compass needle is allowed to rotate about a horizontal axis, it will point straight down). There is only one location where this occurs, near (but distinct from) the Geographic North Pole and the Geomagnetic North Pole.
epicycles were orbits within orbits used to explain discrepancies between expected and observed planetary movement, including the appearance of planets slowing down, speeding up, and moving backward.
