In late 2015, astronomers began studying a nearby star known as a red dwarf. Then, last summer, they concluded that three Earth-sized planets were orbiting the red star, in its temperate zone, where temperatures are just right for liquid water, and perhaps even life, reports Marina Koren.
This was an important find, says Koren, because for years scientists had only focused on stars like our sun searching for habitable planets outside our solar system. Red dwarfs were thought to be too small and too cool to create hospitable conditions.
They’re also harder to detect but astronomers stuck with it and collected hundreds of hours worth of observations of the star known as TRAPPIST-1.
TRAPPIST-1 and its seven planets cannot be imaged directly but powerful telescopes can sweep for biomarkers like oxygen and other exhalations of life, Koren points out.