  We present a method for measuring the Sun's motion using the proper motions
of Galactic halo star streams. The method relies on the fact that the motion of
the stars perpendicular to a stream from a low-mass progenitor is close to zero
when viewed from a non-rotating frame at rest with respect to the Galaxy, and
that the deviation from zero is due to the reflex motion of the observer. The
procedure we implement here has the advantage of being independent of the
Galactic mass distribution. We run a suite of simulations to test the algorithm
we have developed, and find that we can recover the input Solar motion to good
accuracy with data of the quality that will soon become available from the
ESA/Gaia mission.
