Beyond the answers - interesting background to this quiz

The element named after a Swedish village

Terbium, symbol Tb, is one of the lanthanides, the row of silvery metals usually tucked away at the bottom of the periodic table. It was discovered in the 1840s by the Swedish chemist Carl Gustaf Mosander, who was working with a mineral from the quarry at Ytterby, a small village near Stockholm. That single quarry gave its name to four elements - yttrium, terbium, erbium and ytterbium - which is why Ytterby is often called the most element-rich place on Earth. Terbium itself is used in green phosphors in older television screens and in some solid-state devices.

The moon race around Jupiter and Saturn

For years Jupiter was the clear winner in the moon count, thanks to its many small captured objects. Saturn has since overtaken it, with well over a hundred confirmed moons, though the totals for both planets keep shifting as astronomers confirm new discoveries and revise old estimates. Most of these moons are tiny, irregular chunks of rock and ice, quite unlike the large, famous ones such as Europa or Titan. The count is therefore less a fixed fact than a running tally.

The river that shaped Mesopotamia

The Euphrates rises in eastern Turkey and flows through Syria and Iraq before joining the Tigris and emptying into the Persian Gulf. Along with the Tigris, it defined Mesopotamia, the "land between the rivers", where some of the world's earliest cities and writing systems emerged. Because several countries depend on it for drinking water, irrigation and hydroelectric power, the river is also a long-running source of political tension in the region.

Jules Verne and the island that was not empty

Jules Verne's The Mysterious Island follows a group of castaways who build a new life on a remote Pacific island after escaping by balloon. The novel is part adventure story and part survival manual, packed with the period's enthusiasm for science and engineering. It also belongs to Verne's loosely connected Voyages Extraordinaires, and its plot links back to two of his earlier books, giving readers a quiet payoff if they know his work.