It may come as a surprise that there are different branches of astrology. A main Eastern form, for example, called Sidereal astrology, looks to the background stars, those famous constellations, as its guide.
The back story: About 2,000 years ago, the astrological signs and the astronomical ones were the same. But not anymore. The locations of the signs are based on the sun's location on the first day of spring. That location in the sky has slowly drifted westward because of something called "precession" -- the earth continually wobbles (a scientific term for a slight motion) every 26,000 years. Since the constellations were first identified, they have shifted some 30 degrees. Translation: The signs have slipped about a month westward, relative to the stars.
What this means to you: If you follow astrology that is linked to the constellations, your sign would go from say, a Gemini to a Taurus. You could even have a 13th sign, Ophiuchus, which you may have read about.
In short, if you follow the Sidereal astrology, the Eastern branch, your sign may have shifted. (And most likely, no surprise to you at all: This news is hundreds of years old).
But for the rest of us, our horoscope, and our signs, are still the same.