Beyond the answers - interesting background to this quiz

The planet that races around the Sun

Mercury is the closest planet to the Sun, and that short orbit makes its year the briefest in the solar system: roughly 88 Earth days. The trade-off is strange. Mercury turns on its axis very slowly, so a single day on the planet lasts about two of its years. If you lived there, your birthday would come around remarkably often - but sunrise would be a rare event.

A wall that divided a city, and the night it opened

The Berlin Wall was built in 1961 to seal off East Berlin from West Berlin, and it stood as the most visible symbol of the Cold War for nearly three decades. On the evening of 9 November 1989, crowds gathered at the border crossings after announcements that travel restrictions would be eased. Guards, unsure of their orders, eventually let people through, and Berliners celebrated on both sides of the wall. German reunification followed less than a year later.

An epic shaped by oral tradition

The Odyssey is attributed to Homer, the ancient Greek poet also credited with the Iliad. Both works began as oral poetry, performed aloud long before they were written down, which is one reason they contain repeated phrases and epithets - handy memory aids for a singer. The poem follows Odysseus on his long, eventful voyage home from the Trojan War, a journey that has inspired countless retellings.

One ocean, many records

The Pacific covers roughly a third of the planet's surface, making it by far the largest of the world's oceans. It holds the deepest known point on Earth, the Mariana Trench, and it touches more coastlines than any other ocean. Its name, meaning "peaceful sea", was given by the explorer Ferdinand Magellan, who happened to cross it in calm conditions.

Hemingway and the pull of Kilimanjaro

Ernest Hemingway wrote "The Snows of Kilimanjaro" in the 1930s; it was published in 1936 and later appeared in a collection of his short stories. The tale follows a writer on safari in Africa who is gravely ill and reflecting on his life and unfinished work. Kilimanjaro itself, a dormant volcano in Tanzania, is Africa's highest peak and one of the few places near the equator with glaciers near its summit.