April 15, 2022
Although Mercury is the closest planet to the Sun, it is not the hottest. The daytime side of Mercury can reach temperatures of up to 800°F (426°C). Venus however, rests consistently at temperatures of approximately 900°F (482°C). Venus maintains this hot temperature due to the thick layer of clouds that covers the planet and acts like a blanket or greenhouse.
On the left, the cratered surface of Mercury experiences extreme temperatures. The lack of clouds means that all the daytime heat is quickly lost to space. On the right, Venus is kept extremely hot by its thick atmosphere which traps the heat from the Sun. Image credit left: NASA/Johns Hopkins University Applied Physics Laboratory/Arizona State University/Carnegie Institution of Washington, right: JPL/NASA