An invisible planet orbiting the pale red dot of Proxima Centauri (seen here alongside its much brighter neighbors, Alpha Centauri A & B) may be the key to understanding Earthlike planets across our galaxy. (Credit: Digitized Sky Survey 2)
Sometimes it takes a while for the meaning of a new scientific discovery to really sink in. In the case of the planet Proxima Centauri b, announced last week, it may take decades or even centuries to fully grasp the importance of what we have found. You see, this is not just any planet: It is similar to Earth in mass, and it orbits its star in the "habitable zone," where temperatures could potentially allow the existence of Earthlike bodies of liquid water. Proxima Centauri is not just any star, either: It is the very nearest one after the Sun, and it is a small red orb whose feeble light makes it relatively easy to study the planet close beside it.
