Why is Venus hotter than Mercury, although Mercury is closer to the Sun?

Mercury is the planet closest to the Sun, so you might expect it to be the hottest. It is not. That title belongs to Venus, the second planet.

Venus is wrapped in a thick atmosphere full of carbon dioxide, a gas that traps heat, under clouds made of sulphuric acid. The trapped heat makes Venus so hot that a metal like lead would melt into puddles on its surface.

In size, Venus is almost the Earth's twin; the Earth is only a little bigger. But in almost every other way it is strange. It spins in the opposite direction from the Earth and most other planets, and it spins very slowly, taking about 243 Earth days to turn round once. Yet because it is close to the Sun, it takes only 225 Earth days to travel all the way round it. So on Venus a day is a little longer than a year.

That leads to some odd sunrises. Because Venus turns backwards, its Sun rises in the west and sets in the east, and it rises only about once every 117 Earth days. Like Mercury, Venus has no moon at all.