|Artist's conception of Venus's atmosphere|
It is a completely different story in Mercury. As it has no atmosphere to trap the heat from the Sun, the temperature ranges from 90K to 700K. This means that it has got one of the hottest and the coldest temperatures in our Solar system. This is because, the side facing the Sun receives the heat directly and it is hot and, other dark side of Mercury receives no heat from the Sun and it has no atmosphere to trap heat which makes it extremely cold. And this is why Venus is hotter than Mercury.