Is Mercury in retrograde? On any given day in 2015, there's a 19 percent chance that, yes, Mercury is in retrograde. And your Twitter feed today will confirm that, yes, Mercury is in retrograde. Your colleagues, friends, sisters, second cousins thrice removed who read Susan Miller as a contemporary-yet-ancient form of religion will also confirm that, yes, Mercury is in retrograde. So what better time to brush up on a little astrology than today, Sept. 17, 2015, the first day of the last Mercury-in-retrograde of this calendar year? We at Curbed wouldn't advocate for just any old horoscope, though: See how closely your star sign aligns with your favorite architects and designers. And for Zeus's sake, remain flexible, allow extra time for travel, and avoid signing contracts—at least until Oct. 9.