The surface temperatures of the solar system's planets are dependent on how close each planet is to the sun. Planets that have atmospheres are better able to retain heat from the sun, affecting the planet's surface temperature.
Mercury, the closest planet to the sun, has one of the highest surface temperatures in the solar system at 465 degrees Celsius. Because Mercury has no atmosphere to hold in heat, it has a wild variation in surface temperature. Its dark side experiences temperatures as low as -185 C.
Venus has a thick atmosphere of sulfur dioxide and carbon dioxide that traps the sun's heat and creates a greenhouse effect. As a result, Venus has an average surface temperature of 460 C.
Although Earth has an average surface temperature of 7.2 degrees, its surface temperature varies widely, ranging from -89.2 to 70.7 C. Mars also shows great variety in its temperature, ranging from -140 to 20 C.
Because it has no solid surface, Jupiter technically has no surface temperature. The temperature in its clouds and gases range from -145 to 21 C. Saturn is also a gas giant with no solid surface; its atmospheric temperature is approximately -175 C.
Uranus is the coldest planet in the solar system, with a surface temperature of -224 C. Neptune, another gas giant, is also very cold, with an upper atmospheric temperature of -218 C.