Why mercury is not the hottest planet in Solar System?

In the grand scheme of the Solar System, the greatest source of energy by far is the Sun. read more

Although Mercury is the closest to the sun, it's not the hottest planet. The hottest planet in our solar system is Venus because it is covered by a thick layer of clouds composed of carbon dioxide and other gases, which prevent the heat from the sun from escaping back into outer space. read more

Mercury is closest to the sun, this is true. However, because of its proximity to the sun it lacks an atmosphere. Mercury's gaseous molecules reached escape velocity long ago and the atmosphere was 'burned off' leaving a vacant wasteland of rock with a similar surface to the earth's moon. read more