 Lunar eclipses happen only when the full moon occurs around either node of its orbit (ascending or descending).Therefore, a lunar eclipse occurs about every six months, and often two weeks before or after a solar eclipse, which occurs during a new moon around the opposite node.Full moons are traditionally associated with insomnia (inability to sleep), insanity (hence the terms "lunacy" and "lunatic") and various "magical phenomena" such as lycanthropy.