A “coherent” radio signal has been detected from an alien planet, suggesting it could be more likely to be habitable. The signal suggests that the planet has its own magnetic field, which is thought to be central to sustaining life on a particular world. On Earth, our magnetic field helps protect us from the high energy particles and plasma that are blasted from the Sun. As such, any alien life is likely to depend on being protected by a similar field. But until now researchers have struggled to confirm whether distant rocky planets have magnetic fields of their own, and...