The south pole of our moon has deeper craters and taller ridges than the north pole. The processes involved in carving out the landscape of our moon appear to have been more forceful at the south pole, compared to the north pole.
Lunar south polar region as imaged by Clementine.
By NASA/JPL-Caltech – This image or video was catalogued by Jet Propulsion Laboratory of the United States National Aeronautics and Space Administration (NASA) under Photo ID: PIA00001., Public Domain, https://commons.wikimedia.org/w/index.php?curid=8941891
Lunar north pole
By NASA/GSFC/Arizona State University – http://wms.lroc.asu.edu/lroc_browse/view/npole (see also http://photojournal.jpl.nasa.gov/catalog/PIA14024), Public Domain, https://commons.wikimedia.org/w/index.php?curid=31697472
Currents in space are made up of positive ions and electrons, with ions moving in the direction of the current, and electrons moving in the opposite direction.
The ions are far heavier than the electrons. Their impacts are more destructive. It follows then that ions coming in from the south and leaving to the north will carve out deeper craters to the south than to the north.
Moon craters can therefore be seen as indicative of a current moving through our solar system from south to north.