Venus, the second planet from the sun, is the hottest planet in the solar system, with surface temperatures of around 864 degrees Fahrenheit, and there is no difference between day and night temperatures on Venus, so there is no time of day where temperatures tend to dip. This high temperature, which is hot enough to melt tin and lead, is due in part to the planet's proximity to the sun, though Venus manages to be much hotter than Mercury, which is the closest planet to the sun. Venus' extreme heat can be attributed mostly to its extremely thick atmosphere, which is 93 times thicker than Earth's atmosphere and composed mainly of carbon dioxide.
Because Mercury is the closest planet to the sun, many people assume that it is the hottest, but it is significantly cooler than Venus because of its comparatively thin atmosphere. Venus is about 30 million miles further from the sun than Mercury, but its gaseous atmosphere is so incredibly thick that it stays much warmer than the rocky Mercury. This atmosphere harbors powerful and swift winds that sweep around the whole planet in a matter of four days, keeping temperatures on Venus stable as it rotates relatively slowly on its axis.