Eclipse August 12, 2026 · Castilla y León / Madrid, Spain
Will mountains block your eclipse view from Sierra de Gredos?
Gredos rises to 2,592 m at Almanzor — high enough to delay sunset by 5–10 minutes for valleys facing southwest. The path of totality just grazes this region; check terrain before committing.
The August 12, 2026 total solar eclipse over Sierra de Gredos happens at very low sun altitude — under 10° in many places. At that altitude, even modest hills or ridges in your western horizon can block the sun completely. This guide covers the high-impact vantage points in Sierra de Gredos and links each to a 3D simulation that uses real Mapbox elevation data + 360° ray-casting to reveal the actual terrain horizon from that exact spot.
Key viewpoints
Hoyos del Espino
40.353°N, -5.171°W
Navarredonda de Gredos
40.359°N, -5.130°W
Arenas de San Pedro
40.211°N, -5.087°W
Plataforma de Gredos
40.297°N, -5.276°W
Drop a pin anywhere — Heliora computes the terrain horizon from that exact point and shows whether the eclipsed sun is visible above it.
Why does terrain matter so much?
- How low will the sun be during the eclipse?
- Across most of Spain the sun will be between 4° and 12° above the horizon at maximum eclipse. At 4°, a 100 m ridge half a kilometre away blocks the sun. At 8°, the same ridge needs to be 1.4 km away to clear it.
- How does Heliora know the actual horizon from my spot?
- Heliora downloads Mapbox Terrain-RGB elevation tiles around your pin and ray-casts 360° outward, sampling elevation every degree of azimuth and computing the apparent angle of the highest point. The result is the real local horizon from your exact GPS coordinate, not the flat-earth horizon.
- Does this work for buildings too?
- Yes — toggle the "buildings" layer in the sky view. Heliora pulls Mapbox 3D building data for the closest 2 km and renders them as occluders. This is critical in cities like Bilbao, Santander, or Madrid where city blocks can hide a low sun.
- Why did you build this?
- Generic eclipse tools tell you the sun's altitude but not whether your real horizon clears it. For a low-altitude eclipse like 2026-08-12 in Spain, that distinction is the difference between seeing totality and seeing nothing at all from a mountain valley.