Venus is the hottest planet in our solar system, even though Mercury sits closer to the Sun. The reason is a runaway greenhouse effect driven by a thick atmosphere that is about 96% carbon dioxide. This article explains how Venus likely started with oceans and a moderate climate, but as the Sun brightened, water evaporated, carbon dioxide accumulated, and temperatures soared to a constant 867 degrees Fahrenheit. It also draws a clear parallel to Earth, where burning fossil fuels releases CO2 and methane, creating feedback loops like thawing permafrost that could accelerate warming. While Earth won't become Venus, the science shows why limiting greenhouse gas emissions matters.
