Actually..... Scorpio is to the afterglow of Sunset as Cancer is to ....... noon-tide and the promise of lunch, Libra is dusky tea-time as the Sun goes down, the Capricornian-Goat of pitch-black midnight descends the hills to the fish-pool of Pisces, drinking the essence of new-day at Sunrise - arising in Aries (a ri se).
Each of the signs 'rule' two-hours of the 24 hour clock. It begins with Aries at 6am, following is Taurus at 8am, Gemini 10am, Cancer noon, Leo 2pm, Virgo 4pm, Libra 6pm, Scorpio 8pm, Sagittarius 10pm, Capricorn midnight, Aquarius 2am and Pisces at 4am.
A careful-study of the inner-meanings of each sign reveals-all. Scorpio is not midnight. It rules the hours 8pm - 10pm - the traditional time to transform from one-mode to another, waking to sleeping, life to death. Sagittarius (the arrow) is 10 - midnight. The 'spirit' shoots like an arrow to the astral-planes - a higher-education process ensues. The dreaming experience whilst one sleeps is governed by the signs that rule the hours of the night. The 'pitch-black' of midnight is Capricorn, the goat.
I hope my answer was of some use to you.