Mercury stations retrograde on October 20, 1921 at 16° Scorpio, and direct on November 9 at 0° Scorpio — 20 days. From the Earth, Mercury seems to back up against the stars as we overtake it, as a car passed on the highway seems to slide backward. Astrology holds it a time for crossed wires and delays. Computed from JPL's approximate orbits; the stations agree with an almanac's to within minutes.