Why have astrological signs changed since the 1940's??!

Why have astrological signs changed since the 1940's??

In my history class, we were looking at newspapers from the 1940's (I don't remember the precise date), and discovered that the astrological signs had all changed. I'm a libra, and I was a sagitaurius according to the calendar back then. I just found it interesting and was wondering if anyone knows why this is.

4 weeks ago
I don't have the cut out because the paper was an antique and extremely fragile.... but I don't believe anyone I spoke to had the same sign according to the charts back then.

Right, that's the first time I've ever heard of that! (granted, I've only been doing Astrology for 9 years so didn't come across everything yet...)

What was the newspaper and can you show us the cut out?

**edit**

at least give me the name of the newspaper, so i can go investigate :p