The hottest planet is not the closest planet to the Sun.

Even though Mercury is the closest planet to the Sun, it is not actually the hottest. Mercury does not have any atmosphere meaning that this planet is only hot in the daytime when it is directly facing the Sun. At this stage temperatures can rise to 425°C but at night the planet’s temperature can drop down to a freezing -180°C. Venus is the hottest planet. Its thick clouds trap the Sun’s heat causing Venus to be a sizzling 500°C all of the time!