I don't give a fuck, I'm Capricorn and not Scorpio. Fuck the new astrologists.
This wasn't devised by astrologists, but rather astronomers.
For classification purposes, astronomers divide the entire celestial sphere into 88 grid-base areas named after constellations, which include more than just the area covered by the classic 'shapes'. Using these areas, the ecliptic (the path on which the sun 'travels' throughout the night sky) traverses through 13 different constellations, including one (Ophiuchus) that isn't part of the traditional zodiac - although various works of fiction like FFT have indeed included it as the thirteenth Zodiac sign, often under a different name.
What happened is that the Minnesota Star-Tribune interviewed a Minneapolis-based astronomer, who explained why the traditional zodiac is complete bunk scientifically and gave the dates that the sun actually processes through the real world ecliptic, which naturally isn't divided so nice and neatly and has been influenced by thousands of years worth of procession. The headlines 'new zodiac' caught on meme-like throughout the internet by people who don't seem to care to read the article closely and never understand much about astronomy in the first place.