Elisabeth Matthews

Three and a half parsecs from the Sun, among the dim stars of the southern sky, hides a world that astronomers have been trying to see for thirty years. Epsilon Indi Ab is a gas giant, cold as a winter night: its temperature is about 275 kelvins, just above the freezing point of water.

In the attic, you find an old, worn suitcase. From the stickers and scratches, you can guess where it's been. Astronomers have long searched for a similar 'sticker' for planets, and thought they found it in carbon monoxide molecules. Ordinary carbon monoxide consists of a carbon-12 atom and an oxygen atom.