Earth is our only example of a habitable planet, so it makes sense to search for Earth-size worlds when we’re hunting for potentially-habitable exoplanets. When astronomers found seven of them orbiting a red dwarf star in the TRAPPIST-1 system, people wondered if Earth-size planets are more common around red dwarfs than Sun-like stars.
A recent study published in the Proceedings of the National Academy of Sciences, a pair of researchers from the University of Florida (UF) examine orbital eccentricities for exoplanets orbiting red dwarf (M dwarf) stars and determined that one-third of them—which encompass hundreds of millions throughout the Milky Way—could exist within their star’s habitable zone (HZ), which is that approximate distance from their star where liquid water can exist on the surface. The researchers determined the remaining two-thirds of exoplanets orbiting red dwarfs are too hot for liquid water to exist on their surfaces due to tidal extremes, resulting in a sterilization of the planetary surface.
The Fermi Paradox won’t go away. It’s one of our most compelling thought experiments, and generations of scientists keep wrestling with it. The paradox pits high estimates for the number of civilizations in the galaxy against the fact that we don’t see any of those civs. It says that if rapidly expanding civilizations exist in the Milky Way, one should have arrived here in our Solar System. The fact that none have implies that none exist.
Many thinkers and scientists have addressed the Fermi Paradox and tried to come up with a reason why we don’t see any evidence of an expanding technological civilization. Life may be extraordinarily rare, and the obstacles to interstellar travel may be too challenging. It could be that simple.
But a new paper has a new answer: maybe our Solar System doesn’t offer what long-lived, rapidly expanding civilizations desire: the correct type of star.
Should we thank our well-behaved Sun for our comfy home on Earth?
Some stars behave poorly. They’re unruly and emit powerful stellar flares that can devastate life on any planets within range of those flares. New research into stellar flares on other stars makes our Sun seem downright quiescent.
We tend to think of our Earthly circumstances as normal. A watery, temperate world orbiting a stable yellow star. A place where life has persisted for nearly 4 billion years. It’s almost inevitable that when we think of other places where life could thrive, we use our own experience as a benchmark.