Astronomers Reclassify GJ 3378b as 2.3-Earth-Mass Super-Earth 25 Light-Years Away
Updated
Updated · spacedaily.com · Jul 13
Astronomers Reclassify GJ 3378b as 2.3-Earth-Mass Super-Earth 25 Light-Years Away
3 articles · Updated · spacedaily.com · Jul 13
Summary
GJ 3378b has been recast from a 5.26-Earth-mass sub-Neptune into a rocky super-Earth with a minimum mass of 2.3 Earth masses, putting it on a short list of nearby worlds worth checking for life.
A new analysis by Paul Robertson's team used wobble data from the Habitable-zone Planet Finder and NEID spectrograph, finding a roughly 21-day orbit that places the planet in its star's habitable zone.
At 25 light-years away, the planet receives about 90% of the starlight Earth gets, but it does not transit its red-dwarf star, leaving astronomers unable to measure its radius or test its atmosphere with James Webb.
That uncertainty is crucial because red dwarfs can strip atmospheres with flares and stellar wind, and GJ 3378b appears to sit near the 'cosmic shoreline' where a planet may either retain air or end up barren.
The revision also overturns the 2024 candidate interpretation rather than refining it, underscoring how early exoplanet detections can shift sharply until future direct-imaging missions in the 2040s test habitability.
Is our new 'habitable' neighbor a barren rock stripped bare by its violent star?
A 'habitable' world is found, but we can't see its air. What will it take to finally glimpse our cosmic neighbors?
GJ 3378b Reclassified: Nearby Exoplanet Now a 2.3-Earth-Mass Rocky Super-Earth in the Habitable Zone
Overview
GJ 3378b, once thought to be a gaseous mini-Neptune, has been reclassified as a potentially rocky super-Earth after a refined measurement of its mass. Originally estimated at 5.26 Earth masses—borderline for a rocky planet—new advanced methods revealed its mass is actually 2.3 Earth masses, making a rocky composition much more likely. This shift highlights the growing precision in exoplanet science and raises GJ 3378b’s profile as a promising target in the search for habitable worlds, especially as future observatories prepare to study planets like it in greater detail.