Carbonatite lava may have carved Venus’s 6,800-km Baltis Vallis, hinting at a temperate past

A 2025 Science Advances study proposes Venus’s Baltis Vallis—the Solar System’s longest channel at about 6,800 kilometers—was formed by unusually mobile carbonatite lava rather than water, with a low-viscosity melt potentially releasing enough CO2 to help drive Venus’s current greenhouse climate; models show carbonatite could travel far under Venusian conditions, but the idea depends on uncertain eruption volumes and gas fractions and remains unproven without direct samples; future missions VERITAS and Envision could test surface composition and channel morphology, though even a positive result would not confirm oceans, life, or a temperate Venus past.