Beyond the answers - interesting background to this quiz

The painting that left home for a bathroom

Leonardo da Vinci began the Mona Lisa around 1503, and it now hangs in the Louvre in Paris, behind glass in a climate-controlled room. The sitter is widely believed to be Lisa Gherardini, the wife of a Florentine silk merchant, though the identification has never been completely settled. What draws crowds is less the subject than the technique: Leonardo softened the edges of her mouth and eyes so that her expression seems to shift depending on where you look.

A river that shaped a capital

The Thames runs through southern England and through the heart of London, past the Houses of Parliament and the Tower of London. It was once the city's main highway for trade, and for centuries it was also alarmingly polluted - the Great Stink of 1858 forced Parliament to act on the city's sewage. Today it is cleaner than at any point in living memory, and seals have been spotted back in its waters.

Fairy tales that were never meant for children

Hans Christian Andersen published The Little Mermaid in 1837 as part of a collection of fairy tales. Unlike the cheerful Disney version, his story ends in sorrow: the mermaid does not win the prince, and her chance at an immortal soul comes at a painful price. Andersen, born into poverty in Denmark, wrote with a melancholy that adults noticed more than children did, and he always insisted his tales were for both.

One planet, two names

Venus is often called the Evening Star because it is bright enough to be mistaken for one, and it appears near the horizon after sunset for part of each year. At other times it rises before the sun and is known as the Morning Star. The two are the same object - the brightest natural light in our sky after the Sun and Moon, thanks to its thick clouds reflecting sunlight back at us.

Why February got shortchanged

The 30-day months are April, June, September and November, a pattern that goes back to the Roman calendar. February ended up with the fewest days because it was the last month of the old Roman year, and by the time the calendar was reformed there was simply less room to spare. The rhyme "thirty days hath September" exists precisely because the system is so easy to forget.