A pulsar is an extremely dense neutron star which is a highly magnetized. As it rotates it emits a beam of electromagnetic radiation which can sweep across the earth at very regular intervals. This causes an observing astronomer to receive regular "pulses" from the star, hence the name. An interesting phenomenon occurring in some of these rotating stars is an event known as a "spin glitch," that is, a quick change in the spin rate of the pulsar due to a shift in mass location and a resulting rotational change in inertia. Imagine a uniformly dense pulsar whose radius is 10.3 km and whose period of rotation is 25.044 ms. The rotation period is observed to suddenly decrease from 25.044 ms to 25.039 ms. If that decrease was caused by a contraction of the star, by what amount would the pulsar radius have had to shrink?