Sun sign (Surya Rashi)
Your Sun sign is the zodiac sign the Sun occupied when you were born. In Vedic astrology it is measured in the sidereal zodiac, so it is usually one sign earlier than your Sun sign in Western horoscopes.
Also known as: sidereal sun sign
The Sun spends about a month in each sign and moves into the next at each Sankranti, around the middle of the month. Sidereal Aries, for example, begins at Mesha Sankranti, about 14 April, whereas the Western, tropical Aries begins around 21 March.
The Sun stands for the soul, vitality, self-respect, the father and authority, so its sign colours your confidence and the way you lead. Jyotish, however, gives more weight to your ascendant and Moon sign, which change far faster and so say more about you as an individual.
Why your sign may change: the two zodiacs now differ by about 24°. If you were born in roughly the first 24 days of a Western sign, your Vedic Sun sign is the one before it. This is a difference of reference point, not a mistake in either system.