Beyond the answers - interesting background to this quiz

A spacecraft with a tragic twin

Challenger was one of NASA's reusable orbiters, and its name carried a tradition: earlier British and American research ships had borne it too. The shuttle flew several missions before breaking apart shortly after launch in 1986, a loss that reshaped how the agency approached safety. Its sister ships, including Columbia and Discovery, continued the programme for years afterwards.

The river that crosses more borders than any other

The Danube is often called Europe's most international river, and the quiz answer of Germany is only its starting point. From the Black Forest it flows east through Austria, Slovakia, Hungary, Croatia, Serbia, Romania, Bulgaria, Moldova and Ukraine before emptying into the Black Sea. Four capital cities sit on its banks, which is why it has served as a trade route and a cultural seam for centuries.

Ravel's single-minded masterpiece

Maurice Ravel wrote Bolero as a ballet score, and it is built on a daring idea: one rhythmic figure and one melody, repeated without real development, while the orchestra grows steadily louder. Ravel was reportedly puzzled by its enormous popularity compared with his other works. Its relentless build has made it a favourite for conductors and a memorable test of orchestral control.

Why Switzerland is CH

On Swiss cars, CH stands for Confoederatio Helvetica, the Latin name for the Swiss Confederation. The choice avoids favouring any of the country's four official languages - German, French, Italian and Romansh - by using a neutral, historical label instead. The Helvetii were the Celtic people who inhabited the region in Roman times.

Californium and the art of naming elements

Californium takes its symbol Cf and its name from the state of California, where it was first produced at a university laboratory in the mid-twentieth century. It belongs to the actinide series and is highly radioactive; one isotope is used as a neutron source in industrial scanning and in starting up nuclear reactors. Many heavy elements follow this pattern of being named after places or scientists.