It’s just convention.
OK, here goes: Conventional Western astrology since Ptolemy (umm…a long time ago) has used a system dividing the year into 4 roughly equal parts (“seasons”), each beginning at an equinox or solstice. Each season is divided into three roughly equal parts called “signs.”
This is where it gets weird: the apparent circuit of the sun in the heaven, or ecliptic, is used to determine the position–at any given time–of each “planet,” or heavenly body, in one of the signs. Because the exact points of the equinoces relative to the stars change a little each year, the signs do too. The sign of Pisces does not actually correspond to the astronomical constellation of the same name, although it sort of did 2000 years ago.
“Sidereal astrologers” actually use the positions of the planets relative to the stars, but even they buy into the whole “12 equal parts” crap.
Too much poking around with charts and books, if you ask me.
Party per bend sinister wavy bendy sinister wavy vert & or, & sable, in fess point a demi-pellet ensorcelled rayonny or inverted & bendwise sinister issuant from the party, in sinister base a roundel bendy sinister wavy vert & or.
Or something… Oh, just go here.
I think you’ve got it slightly off, foolsguinea. The ecliptic is, of course, the apparent path of the sun’s circuit through the sky, but it wasn’t used to determine the position of the five visible planets. Given the nature of the solar system the planets roughly follow the ecliptic but the only way astrologers determined the location of the planets was to go outside and look.
Additionally, although the ancient astrologers can’t be blamed for this as it’s a recent astronomical convention, the ecliptic passes through the constellations of Ophiuchus and Cetus for a couple of days, as shown graphically in this really kick-ass astronomical skychart called Uranometria 2000. A quick look at the Old Farmer’s Almanac for 2000 shows that the Moon also will pass into Cetus on April 4th, Pisces on the 5th, and back into Cetus on the 6th. On the 22nd it’ll spend the day in Ophiuchus.
So there you have it - modern astrologers aren’t taking everything into account. Neener neener.
All I wanna do is to thank you, even though I don’t know who you are…