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Gliese 3378b Revised: 2.3 Earth-Mass, 21-Day Habitable Orbit

7/3/2026

Summary

Story summary

Astronomer Paul Robertson measured Gliese 3378b’s mass at 2.3 Earth masses and period at 21.45 days, overturning the earlier 5.26 Earth-mass, 24.73-day estimate using data from Habitable-zone Planet Finder, NEID, CARMENES and SPIRou.
The planet orbits red dwarf Gliese 3378 in Camelopardalis within the habitable zone, receiving about 90 % of Earth’s solar radiation.
Because it does not transit, the planet’s radius and atmosphere remain unknown, though the 2040s Habitable Worlds Observatory may detect an atmosphere.

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Story summary

Astronomer Paul Robertson measured Gliese 3378b’s mass at 2.3 Earth masses and period at 21.45 days, overturning the earlier 5.26 Earth-mass, 24.73-day estimate using data from Habitable-zone Planet Finder, NEID, CARMENES and SPIRou.
The planet orbits red dwarf Gliese 3378 in Camelopardalis within the habitable zone, receiving about 90 % of Earth’s solar radiation.
Because it does not transit, the planet’s radius and atmosphere remain unknown, though the 2040s Habitable Worlds Observatory may detect an atmosphere.