Why is a day on Venus longer than its year?

Because it spins extraordinarily slowly - 243 Earth days for one rotation, against 225 to go round the Sun. It also spins backwards, so on Venus the Sun rises in the west, and because the two motions combine, the interval from one sunrise to the next works out at about 117 Earth days.

Nobody is certain why. The leading explanations are a colossal early impact that flipped or halted it, or the Sun's tidal pull on Venus's massive atmosphere acting as a brake over billions of years - an atmosphere ninety times heavier than ours, which itself races round the planet in four days, far faster than the ground beneath it.

The surface is about 465 degrees Celsius, hot enough to melt lead and hotter than Mercury despite being further out, because carbon dioxide holds the heat in. Soviet Venera landers reached the surface in the 1970s and returned the only photographs anyone has; the longest survived 127 minutes before the heat and pressure destroyed it.