When the Sun Stands Over Lima: The October 27 Zenith

Lima, Peru sits at 12° South latitude. Because it's south of the Equator, the sun passes directly overhead (zenith) twice a year—once moving south, once moving north. The first zenith passage after the September equinox occurs on October 27.

The Geometry

• Subsolar point moves between Tropic of Cancer (23.5°N) and Tropic of Capricorn (23.5°S)
• Crosses 12°S on its southward journey ~34 days after Sep 23 equinox → Oct 27
• Crosses again northward ~34 days before Mar 20 equinox → Feb 14

What "Overhead" Means

• Solar altitude = 90° (shadows vanish beneath objects)
• Occurs at local solar noon (~11:45 AM PET, Peru Time, UTC-5)
• Only locations between 23.5°N and 23.5°S experience this

Lima's Unique Climate Context

Despite the overhead sun, Lima is cool and cloudy (garúa mist) due to the cold Humboldt Current. October is spring—temperatures ~18–22°C (64–72°F). The zenith sun is often hidden by stratus.

Cultural Note

Ancient Lima cultures (Lima, Wari, Ichma, Inca) built huacas (pyramids) aligned to zenith passages. At Pachacamac and Huaca Pucllana, sunlight enters specific chambers only on these days—agricultural calendar markers.

So on October 27, if the garúa lifts, a vertical stick in Lima casts no shadow—a celestial alignment witnessed for millennia.