The Zodiac zero point formerly signaled the start of spring in the Northern Hemisphere. The vernal equinox occurs on March 21 when the ecliptic and celestial equator meet.
Ancient astrologers were unaware that Earth wobbles about its axis every 25,800 years. Precession is generated by the moon's gravity on Earth's equatorial bulge.
Zero was in Aries in 600 B.C., termed the "first point of Aries." Aries covered the first 30 degrees of the ecliptic, Taurus 30–60 degrees, Gemini 60–90 degrees, and so on for all 12 Zodiac constellations.
This wobble has moved the crossing point between the celestial equator and the ecliptic west by 36 degrees, or roughly one-tenth of the way around
Aries are people born March 21–April 19. The sun is no longer in Aries for much of that time. From March 11 to April 18, the sun is in Pisces!
This table shows the times when the sun is in the Zodiac's astronomical constellations, according to contemporary constellation borders and adjusted for precession (these dates may change a day from year to year).
Once precession is considered, your Zodiac sign will likely change. If you were born between Nov. 29 and Dec. 17, you are an Ophiuchus, which you never saw in the papers!