The traditional East Asian calendars divide a year into 24 solar terms . Shuāngjiàng or Sōkō is the 18th solar term. It begins when the Sun reaches the celestial longitude of 210° and ends when it reaches the longitude of 225°. It more often refers in particular to the day when the Sun is exactly at the celestial longitude of 210°. In the Gregorian calendar, it usually begins around October 23 and ends around November 7.