star are the "glitches" observed in the rotation velocity of the neutron star. This velocity decreases slowly but steadily, except for an occasional sudden variation – a “glitch”. One model put forward to explain these glitches is that they are the result of “starquakes” that adjust the crust of the neutron star. Models where the glitch is due to a decoupling of the possibly superconducting interior of the star have also been advanced. In both cases, the star's moment of inertia changes, but its angular momentum does not, resulting in a change in rotation rate.