It is often discussed within the community of exoplanet scientists that a danger lies in the description of intriguing exoplanets as “Earth-like.”
Nothing discovered so far warrants the designation, which is pretty nebulous anyway. Size and the planet’s distance from a host star are usually what earn it the title “Earth-like,” with its inescapable expectation of inherent habitability. But residing in a habitable zone is just the beginning; factors ranging from the make-up of the planet’s host star to the presence and content of an atmosphere and whether it has a magnetic field can be equally important.
The recent announcement of the detection of a planet orbiting Proxima Centauri, the closest star to our own, set off another round of excitement about an “Earth-like” planet. It was generally not scientists who used that phrase — or if they did, it was in the context of certain “Earth-like” conditions. But the term nonetheless became a kind of shorthand for signalling a major discovery that just might some day even yield a finding of extraterrestrial life.
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