Libra is the Scales, the only constellation on the Sun’s path that is an object rather than a creature or a person, and once not even that: its two brightest stars, Zubenelgenubi and Zubeneschamali, are Arabic for the southern and northern claw, from when they belonged to the Scorpion next door. The Sun is in Libra through most of November. The horoscope’s Libra runs from late September, a full constellation earlier.
The dates above are computed for 2026 from the constellation boundaries the International Astronomical Union fixed in 1930. They move by about a day every seventy years, so they are good for a lifetime, and for the particular day you were born the calculator will check the boundary itself.