When Neil Armstrong first stepped on the Moon on July 20, 1969, the Moon was transiting through Capricorn - the sign of achievement, ambition, structure, and reaching the highest peaks.
Capricorn is ruled by Saturn, representing discipline, hard work, and mastery over challenges. The symbolism of humanity's greatest achievement happening while the Moon was in this ambitious sign is remarkably fitting.
Additionally, the mission launched when the Sun was in Cancer, the sign ruled by the Moon - a cosmic reflection of the mission's lunar destination.