Scientists Discover Earth-Like Exoplanet GJ 3378b Orbiting Red Dwarf Star

Key Facts

• Exoplanet Name: GJ 3378b
• Host Star: Gliese 3378, a red dwarf star
• Distance from Solar System: Approximately 25 light-years
• Constellation: Camelopardalis (northern sky)
• Mass: About 2.3 times the mass of Earth (revised from initial ~5.3 Earth masses)
• Orbital Period: 21.45 days (revised from initial ~25 days)
• Location: In the habitable zone of its host star
• Stellar Radiation Received: Approximately 90% of the solar radiation Earth receives from the Sun
• Discovery Method: Radial-velocity observations
• Instruments Used: Habitable-zone Planet Finder on the Hobby-Eberly Telescope at McDonald Observatory (Texas); NEID Spectrometer on the WIYN Telescope (Arizona)
• Revised Data Published: July 1, 2026

Background & Context

Exoplanets are planets orbiting stars beyond our Solar System. GJ 3378b orbits a red dwarf star, which is a low-mass, cooler star type common in the Milky Way galaxy. Its host star is faint and located in the northern constellation Camelopardalis, making precise measurements challenging.

The habitable zone, also known as the circumstellar habitable zone, is the region around a star where conditions might be right for liquid water to exist on a planet's surface if the planet has a suitable atmosphere, a key factor for potential habitability.

Initial estimates placed GJ 3378b's mass around 5.3 Earth masses with an orbital period near 25 days; revisions from the 2026 study lowered the mass to about 2.3 Earth masses and orbit to approximately 21.45 days, indicating a closer orbit within the habitable zone.

Detection utilized the radial-velocity method, which measures small changes in a star's motion caused by gravitational tugs from orbiting planets. This technique helps estimate the planet’s mass and orbital parameters.

Why This Matters for Exams / Exam Relevance

This discovery encapsulates key concepts often tested in exams relating to astronomy, planetary science, and astrophysics, especially in competitive exams requiring detailed understanding of exoplanet detection, stellar types, and habitability criteria.

Understanding the classification of stars (red dwarfs), the concept of habitable zones, detection techniques like radial velocity, and instrumentation (e.g., HET and NEID) is important for exam readiness.

Moreover, the refined data and scientific process exemplify how astronomical measurements evolve, highlighting critical thinking about observational data interpretation—valuable for higher-level questions and essay-type responses.

Points to Remember

• GJ 3378b was first identified in 2024, with re-analysis refining its characteristics published in 2026.
• It orbits a red dwarf star in Camelopardalis, approximately 25 light-years from Earth.
• The planet's mass is about 2.3 Earth masses, lower than initial estimates, indicating a more Earth-like nature.
• Its orbital period is 21.45 days, placing it firmly within the host star’s habitable zone.
• Receives about 90% of the solar radiation Earth does, near the inner edge of the habitable zone.
• Discovery was made using radial-velocity measurements with the Habitable-zone Planet Finder (HET) and NEID Spectrometer (WIYN Telescope).
• Scientists have not yet confirmed the presence of an atmosphere, which is crucial for liquid water and life potential.
• Future atmospheric studies are planned using NASA’s Habitable Worlds Observatory, expected in the 2040s.