  Sunspots are cool areas caused by strong surface magnetic fields inhibiting
convection. Moreover, strong magnetic fields can alter the average atmospheric
structure, degrading our ability to measure stellar masses and ages. Stars more
active than the Sun have more and stronger dark spots than in the solar case,
including on the rotational pole itself. Doppler imaging, which has so far
produced the most detailed images of surface structures on other stars than the
Sun, cannot always distinguish the hemisphere in which the starspots are
located, especially in the equatorial region and if the data quality is not
optimal. This leads to problems in investigating the north-south distribution
of starspot active latitudes (those latitudes with more spot activity), which
are crucial constraints of dynamo theory. Polar spots, inferred only from
Doppler tomography, could plausibly be observational artifacts, casting some
doubt on their very existence. Here we report imaging of the old,
magnetically-active star $\zeta$ Andromedae using long-baseline infrared
interferometry. In our data, a dark polar spot is seen in each of two epochs,
while lower-latitude spot structures in both hemispheres do not persist between
observations revealing global starspot asymmetries. The north-south symmetry of
active latitudes observed on the Sun is absent on $\zeta$ And, which hosts
global spot patterns that cannot be produced by solar-type dynamos.
