Mercury endures a complicated relationship with our Sun. It is bound in a complex dance with an erratic orbit which makes it seem to be tidally locked (showing only one side to the Sun). In fact Mercury slowly rotates around three times for every two times it revolves around the Sun but the effect on this tortured celestial body is the same. The planet’s day side is an incandescent 430ºC and the night side a bone-chilling -180ºC.