The most common stars in the Milky Way go by a less-than-
ennobling name: M-dwarfs. You may or may not have heard of them,
but you’ve definitely never seen one — at least not with the
naked eye. Even the very nearest M-dwarf is too dim to be
spotted without a telescope, so until astronomers began scanning
the sky in real detail, nobody had guessed these small, reddish
stars even existed. “If the Sun is a hundred-watt bulb,” says
Harvard astronomer David Charbonneau, “M-dwarfs are Christmas-
tree lights.” But M-dwarfs make up for their low wattage with
sheer numbers. A whopping 248 M-dwarfs (and counting) are
sprinkled right in the Sun’s immediate neighborhood, compared
with a mere 20 or so Sun-like stars. Now, a new analysis says
that at least one of those M-dwarfs is likely to host a
habitable, Earthlike planet. Where there is one such familiar
world, there are probably more. “The punchline,” says Courtney
Dressing, the Harvard graduate student who led the analysis, “is
that the nearest Earthlike planet should