Venus in culture the night sky, and follows a synodic cycle by which it seems to disappear for several says due to its proximity to the sun, then re-appear on the opposite side of the sun and on the other horizon. Depending on the point in its cycle, Venus may appear before sunrise in the morning, or after sunset in the evening, but it never appears to reach the apex of the sky. Therefore, many cultures have recognized it with two names, even if their astronomers realized that it was really one object. In old English, the planet was known as "morgensteorra" (morning
Stability of the Solar System essentially the distance from sun to earth). These are now known as the Kirkwood gaps. Some asteroids were later discovered to orbit in these gaps, but their orbits are unstable and they will eventually break out of the resonance due to close encounters with a major planet. Another common form of resonance in the Solar System is spin–orbit resonance, where the period of spin (the time it takes the planet or moon to rotate once about its axis) has a simple numerical relationship with its orbital period. An example is our own Moon, which is in a 1:1 spin–orbit resonance