Beyond the answers - interesting background to this quiz

A gas that shields us by day and harms us by night

Ozone is a molecule made of three oxygen atoms, which is why its formula is O3 rather than the O2 we breathe. High in the stratosphere, this unstable gas forms a protective layer that absorbs most of the sun's harmful ultraviolet radiation. Closer to the ground, however, ozone is a pollutant and a key ingredient of urban smog, so the same molecule can be both a guardian and a hazard.

Jules Verne's journey that predated real spaceflight

From the Earth to the Moon, published by Jules Verne in 1865, imagined a crew of Americans launched toward the Moon from a giant cannon in Florida. Verne was already famous for Twenty Thousand Leagues Under the Seas and Around the World in Eighty Days. His blend of meticulous technical detail and bold speculation helped establish what we now call science fiction, and his choice of a Florida launch site still reads as an uncanny coincidence.

Indonesia's restless volcanic landscape

Indonesia sits along the Pacific Ring of Fire, a belt of intense seismic and volcanic activity that traces the edges of several tectonic plates. With well over a hundred active volcanoes spread across its many islands, the country experiences eruptions and earthquakes far more often than most nations. The fertile volcanic soil that draws farmers to these slopes is the same force that makes life there unpredictable.

Calendars are more varied than you might think

The Gregorian calendar, introduced by Pope Gregory XIII in the sixteenth century, is the world's most widely used civil calendar, but it is not universal. A small number of countries, including Saudi Arabia and Iran, rely on other systems for official purposes. Even where the Gregorian calendar dominates, many cultures track religious or traditional dates using lunar or lunisolar calendars alongside it.

The Andaman Sea, a crossroads of the Indian Ocean

The Andaman Sea lies in Southeast Asia, bordered by Myanmar, Thailand, Malaysia and the Indian territory of the Andaman and Nicobar Islands. Despite its tropical beauty, it is one of the most seismically active stretches of ocean on Earth. The 2004 Indian Ocean earthquake, whose epicentre was nearby, triggered the tsunami that devastated coastlines around the region.