We have slightly odd numbering here. Gemini 7 (VII) was launched on December 4th, 1965, after Gemini 5, but before Gemini 6A. Gemini 6 was obviously originally planned to go between 5 and 7, but had to be cancelled and rescheduled with an “A”.
The plan for Gemini 7 was to observe the effects of prolonged spaceflight on astronauts. The two-man crew, Frank Borman and James Lovell, circled the globe 206 times during their two week confinement. After 11 days they were joined briefly by Walter Schirra aboard Gemini 6A, and practised rendezvousing (at closest approach they were just one foot apart).
Gemini, of course, is the constellation that lies between Cancer and Taurus in the sky (and therefore in the zodiac) and is historically associated with the twin brothers Castor and Polydeuces (or Pollux if you prefer the later Roman name). I prefer Polydeuces myself, because the translation is “much sweet wine”, which you just don’t get with “Pollux”. Castor, as any rodentologist will tell you, is Greek for “beaver”.
The twins now immortalized in the heavens were collectively known to the Greeks as the Diskouri, or “sons of Zeus” (the noun Gemini is from Roman mythology). They also had twin half-sisters, even more famous than themselves: Helen (of Troy) and Clytemnestra.