An artist’s impression of the Earth-size exoplanet TRAPPIST-1e, depicted at the lower right, is silhouetted as it passes in front of its host star. Scientists call this event a transit. Credit: NASA, ESA, CSA, J. Olmsted (STScI).Astronomers have seen tentative evidence for an atmosphere on TRAPPIST-1e, an Earth-sized rocky planet 40 light years away.
