This space quiz launches you around the solar system, from scorching Mercury and dusty Mars to giant Jupiter and a planet that rolls along on its side. You'll also meet the pioneers of human spaceflight and find out how long sunlight takes to reach us. Ten questions range from easy to astronomical, each with a quick explanation that makes the universe a little less mysterious.
Our solar system is full of worlds that break the rules we learn on Earth. Venus, for example, spins so slowly that a single day there lasts longer than its entire year. And Pluto, once taught as the ninth planet, was reclassified as a dwarf planet by the International Astronomical Union in August 2006, which is why older textbooks and newer ones don't always agree.
Space trivia mixes two kinds of knowledge. Some questions are about the planets themselves: their size, color, moons and strange features. Others are about the people and missions that explored them during the space race between the United States and the Soviet Union, when firsts were being set at an astonishing pace in the 1950s and 1960s.
A handy tip is to sort the planets into two families. The four inner planets are small and rocky, while the outer giants are huge balls of gas and ice with dozens of moons and powerful storms. Knowing which family a planet belongs to will often help you rule out wrong answers. Distances in space are so vast that even simple numbers can feel unreal, so trust the scale and go with your best estimate.