Since many of the 12 astrological signs (zodiacal constellations) may be visible in any single night, based on what is determined that this month (for 30 days!) is Capricorn, or Aquarius or Pisces etc.? Based on what in astronomy is this determined? What is the astronomical logic in it?
I've been told that the sun 'blocks' always one star constellation, so assuming the night is longer than the day (14-16 hours), and the earth rotates 15 degrees each hour and one star constellation appears while one disappears, it means that by 14 hours 6 'new' star consolations (that couldn't be visible at the beginning of the night) now can be seen along the night. This would mean that 12 star constellations may be visible every day (once 24 hours). If my reasoning is correct, what was the astronomic basis for the claim that one star constellations (out of the specific 12) is 'blocked' for one month?