The closest alien planet to our solar system is even more Earth-like than scientists had thought, new observations suggest.

In a new study, an international team of researchers found that Proxima b, which lies just 4.2 light-years from Earth, is just 17% more massive than our planet. 

Previously, scientists thought that this exoplanet, which lies in the habitable zone of its star, harbored about 1.3 Earth masses. The new measurement indicates that Proxima b is even more like our home planet, at least in size, than previous observations led scientists to think. 

The research team studied Proxima b using the Echelle Spectrograph for Rocky Exoplanet and Stable Spectroscopic Observations, or ESPRESSO for short.  ESPRESSO is a Swiss spectrograph that is currently mounted on the European Southern Observatory's (ESO) Very Large Telescope in Chile. Spectrographs observe objects and split the light coming from those objects into the wavelengths that make it up so that researchers can study the object in closer detail.

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