There are 150 to 450 planets in our solar system. The desire to keep the number small is a cultural bias from the prescientific days when planets were viewed as gods reigning in their orbits, ruling our lives through the horoscope. The essence of that meme still survives... /1
2/ The names of the days of the week are from the names of the 7 ancient planets (which included the Sun and Moon as planets)
Saturn(n)-day
Sun-day
Moon-day
(The rest in Spanish)
Miercolos = Mercury
Martes = Mars
Jueves = Jove or Jupiter
Viernes = Venus
Similar in Anglo-Saxon
Saturn(n)-day
Sun-day
Moon-day
(The rest in Spanish)
Miercolos = Mercury
Martes = Mars
Jueves = Jove or Jupiter
Viernes = Venus
Similar in Anglo-Saxon
3/ The days of the week were named as part of a horoscope system so people could always know which planet was ruling at any given moment. It was a deep desire to find order and meaning in life, looking to the seemingly powerful lights in the sky for that.
4/ Ever since then, there has been a persistent cultural desire to have a simple solar system with just a few, memorizable planets in sequence. But Galileo redefined "planet" to include big moons. Planetary scientists still use "planet" terminology that derives directly from him.
