David Kipping

The hunt for exomoons — the search for satellites around planets of other stars — resembles watching shadows in a theater where the spotlight keeps fading and flaring. The planet Kepler-167e, a gas giant near a scorching star, was discovered by William Borucki and his team.

The galaxy is like a city at night: most windows shine steadily, but sometimes a skyscraper lights up all its lights and then goes dark. Just like that, according to a new hypothesis about planets around alien stars (exoplanet), we might first notice another civilization — by a short but blinding flash that could mark its demise.

Earth is like dough mixed to a precise recipe: two parts water to one part land. Too much water, and the planet becomes a vast ocean where intelligence has nothing to grasp onto. Too much land, and water retreats deep, leaving a desert. Scientists put this culinary analogy to the test with statistics.

The hunt for life on distant planets is like diagnosing a rare disease with a test of unknown accuracy. A single positive result means nothing: maybe it's a glitch? We search the atmospheres of exoplanets (worlds around other stars) for traces of water and other compounds, but any signal could be a false alarm.