The so-called gyro effect, that is, rotating objects with the same effect as gyro. The gyro has two characteristics of precession and fixed axis. When the high-speed rotating gyroscope encounters an external force, its direction of the shaft does not change with the direction of the external force, but the shaft is centered around a fixed point. If you play gyro will know, gyro rotation on the ground when the axis will continue to twist, which is precession. In short, the gyro effect is the rotation of the object has to maintain its direction of rotation (the direction of the rotation axis) inertia.