Astronomers have discovered that a nearby exoplanet called GJ 3378b may be much more Earth-like than scientists first believed. Located about 25 light-years from Earth in the constellation Camelopardalis, the planet orbits a small, cool red dwarf star. GJ 3378b lies inside its star’s habitable zone, the region where temperatures may allow liquid water to exist on the surface. Since water is considered essential for life as we know it, this makes the planet one of the most promising nearby worlds in the search for extraterrestrial life.
Researchers used the Habitable-zone Planet Finder instrument on the Hobby-Eberly Telescope at McDonald Observatory to study the planet in greater detail. Instead of observing the planet directly, they measured the tiny wobble in its host star caused by the planet’s gravity. This technique allowed scientists to calculate the planet’s mass and orbit with much greater accuracy. The new observations revealed that GJ 3378b is significantly lighter than previously estimated. When it was discovered in 2024, astronomers believed it was about five times the mass of Earth. The latest analysis shows it is actually only 2.3 times Earth’s mass.
This revised estimate is important because smaller super-Earths are more likely to be rocky planets, similar to Earth, rather than worlds surrounded by thick, crushing atmospheres that would make life far less likely. Scientists also updated the planet’s orbital period. Earlier measurements suggested it completed one orbit in 25 days, but the new study shows it circles its star every 21 days. Although this is much shorter than Earth’s 365-day orbit, the planet still remains within the habitable zone because its red dwarf star is much cooler and smaller than the Sun.
However, researchers caution that being close to a red dwarf could expose the planet to intense stellar radiation. Such radiation may gradually strip away its atmosphere, potentially reducing its chances of supporting life. More observations will be needed to determine whether GJ 3378b has retained a stable atmosphere. Red dwarfs are the most common type of star in the Milky Way, making up nearly 70% of all stars in our galaxy. Understanding the planets that orbit these stars is considered essential in the search for life beyond our solar system.
The discovery also prepares scientists for future missions. Powerful next-generation observatories, including the Giant Magellan Telescope, the Extremely Large Telescope, and the Habitable Worlds Observatory, are expected to study planets like GJ 3378b in greater detail. These telescopes may eventually detect biosignatures, or chemical signs that could indicate the presence of life. Although scientists cannot yet confirm whether GJ 3378b is inhabited, the new findings make it one of the most exciting nearby super-Earths for future exploration. As researchers continue studying planets around nearby stars, discoveries like this bring humanity closer to answering one of its biggest questions: Are we alone in the universe?
