What is the tropical zodiac?

Signs here are measured from the point where the Sun stands at the March equinox, so Aries always begins with spring in the north. Because the Earth’s axis slowly wobbles, that starting point has slid about a sign’s width against the stars since the system was set, which is why the Sun is usually in front of a different constellation from its tropical sign. The sidereal zodiac most Indian astrologers use measures its twelve equal signs from the stars instead; in its most common version the two differ by just over 24 degrees today.