♊ Gemini — ecliptic 60° to 90°

Mercury rules two signs, and they are not a gentle pair in this geometry. Gemini’s center is 75°. Virgo’s center is 165°. The separation is 90°, which is a square, and the square orb is 8°. So the two Mercury-ruled signs meet the engine as a square, not as a conjunction and not as a trine. Sharing a ruler does not create an aspect. The aspect is the angle between the longitudes.

The window itself stops at 90.0°, the same longitude as the tropical Cancer ingress. A planet at 89.5° is still Gemini. A planet at 90.0° has entered Cancer. That boundary is sharper than a horoscope column usually admits, and it is the boundary the birth-chart route uses when it labels the Sun.

Air signs are spaced 120° apart, so the trines from Gemini are Libra and Aquarius. The opposition, 180° away, is Sagittarius. Pisces and Virgo are the squares — Virgo being the other Mercury sign. Aries and Leo are the sextiles at 60°, orb 6°. Taurus and Cancer are the 30° neighbors and are not scored. The Moon can cross this 30° sector in about two and a half days, so a Gemini sun sign says nothing stable about the Moon sign. The rising sign moves faster still.