Of all the challenges presented in this book, this chapter should be considered the great equalizer. All of the objects to come in later chapters require some level of auxiliary equipment – binoculars or a telescope – in order to be seen. But not these. The targets described below require only one piece of optical equipment: your eyes. That's right, we're about to go nude stargazing together!

While some readers will enjoy distinct advantages over others in the chapters to come in terms of equipment, here we are as close to on a level playing field as possible. That's the fun of it. It's amazing just what can be seen by eye alone when you really make a concerted effort under dark skies.

Has anyone ever asked you “What is the most distant object visible to the naked eye?” Probably? It could have been someone at a club star party or maybe a family member at a reunion who is bemused by your interest in astronomy, but most astronomers have been asked that question before. What did you tell them? More likely than not, most city slickers would give the stock answer that we have all used: M31, the Andromeda Galaxy (naked-eye Challenge 11), which by modern reckoning is 2.5 million light years away. Those who live farther from civilization, without the pall of light pollution shrouding their sky, may have answered M33, the Triangulum Galaxy (naked-eye Challenge 12), which is 2.9 million light years away.