“Laws of nature mixed with evolutionary/historical contingencies allow for a range of diversity… [t]hat diversity, within the laws of nature, when I step back a bit from the desk or the computer, still surprises me to no end.” -Adrian Lenardic
When it comes to the habitability of a planet, there are a lot of assumptions that we make. All of them boil down to, at some level or other, how Earth-like this world is. This is reflected in our language: terms like “super-Earth” or “habitable zone” showcase this inherent bias. Yet the vast majority of stars that are out there aren’t Sun-like, and the vast majority of worlds with life on them may not be very Earth-like at all.
Different colors, masses and sizes of main-sequence stars. The most massive ones produce the greatest amounts of heavy elements the fastest. Image credit: Wikimedia Commons users Kieff and LucasVB; annotations by E. Siegel.
Rather than consider whether a world has a large Moon, rotates on its axis, has tectonic plates or is susceptible to flares from its star, we should be focusing on the actual conditions present there. The speculation we engage in now, given our insufficient information, may result in us closing ourselves off to not only the possibility that life may exist elsewhere, but that Earth-like life may, in fact, be the rarity.
TRAPPIST-1 system compared to the solar system; all seven planets of TRAPPIST-1 could fit inside the orbit of Mercury. Note that at least the inner six worlds of TRAPPIST-1 are all locked to the star. Image credit: NASA / JPL-Caltech.
Despite what you may have heard from some skeptics, Proxima b and the worlds around TRAPPIST-1 may be potentially habitable after all. Come find out how!