Gemini

It's Gemini, the third sign of the zodiac. In Western astrology Gemini is an air sign ruled by Mercury, traditionally linked with talk, curiosity and restlessness. The running jokes about Geminis having “two sides” lean on the twins image.

In a chart discussion, check the label. A Gemini Moon doesn't make Gemini the person's Sun sign, which comes from where the Sun stood at birth. Born right at the May or June changeover? The exact switch date shifts slightly from year to year.

Why does ♊ look like a Roman two?

It is traditionally read as the twins, bound together. The two uprights are usually taken as Castor and Pollux, twin brothers of Greek myth, with the bars tying them; historians also offer other explanations of the shape. Babylonian astronomers already saw “Great Twins” in this part of the sky, and the constellation's two brightest stars carry the names Castor and Pollux.

The sign and the constellation are different things: the sign is a fixed slice of the zodiac, and the slow wobble of Earth's axis means the Sun now crosses the Gemini stars on other dates. App, font and text-versus-emoji display change how ♊ looks, never which sign it means.