The hottest planet in the solar system is Venus. Despite being second from the Sun, Venus has an extreme greenhouse gas effect due to its thick atmosphere, primarily composed of carbon dioxide. This traps heat efficiently, causing surface temperatures to reach around 900 degrees Fahrenheit (475 degrees Celsius). The situation is further exacerbated by a lack of substantial natural features (like oceans) that can moderate its temperature. Venus' scorching conditions make it even hotter than Mercury, the closest planet to the Sun, revealing the complexities of planetary atmospheres and their effects on temperature.