Western astrology starts the zodiac at the March equinox, Vedic astrology at the stars, and the two sit about 24° apart. So the Sun reaches Gemini about 24 days later in the Vedic zodiac, and most people with a Western Gemini Sun have a Vedic Taurus Sun.
When the Sun is in Gemini
Western Gemini
21 May – 20 Jun
Vedic Gemini
15 Jun – 15 Jul
Western Gemini: your Vedic Sun
Born 21 May – 14 Jun
Vedic Sun in Taurus
Born 15 Jun – 20 Jun
Gemini in both zodiacs
Dates for someone born around 1990, in UTC. They move a day either way with the birth year and time; a chart in Unseen Signs is exact to the minute.
The nakshatras of Vedic Gemini
Vedic astrology also divides the sky into 27 nakshatras, the lunar mansions. Vedic Gemini holds:
The same 24° shift applies to every planet and to the rising sign, so most charts change in several places at once. Your birth date, time and place show your Sun, Moon and rising sign in both zodiacs.