Venus: Earth's near-twin turned runaway-greenhouse furnace

Venus is almost Earth’s twin in size but hosts a surface around 465°C under about 92 times Earth’s atmospheric pressure, due to a runaway greenhouse that likely began when oceans evaporated as the Sun brightened. The planet may have started habitable before losing its water, contrasting with Mars’ fate. Now NASA’s DAVINCI and VERITAS and Europe’s EnVision will probe whether Venus was ever wet and what pushed it into a lethal climate—lessons about how narrow the conditions for habitability really are.