A nearby planet that could one day help answer one of humanity’s biggest questions—whether life exists beyond Earth—may be more promising than scientists first believed.
Astronomers have taken a closer look at an exoplanet called GJ 3378b, a planet outside our solar system, and found that it may be much more Earth-like than earlier studies suggested.
The findings, published in The Astrophysical Journal, show the planet is probably smaller and rockier than first estimated, making it a stronger candidate in the search for life.
GJ 3378b is located about 25 light-years from Earth in the direction of the constellation Camelopardalis.
While that is an enormous distance for humans, it is considered relatively close in our part of the Milky Way galaxy.
The planet orbits a small, cool star known as a red dwarf. Red dwarfs are much smaller and dimmer than our sun and are the most common type of star in the galaxy.
In fact, about 70% of all stars are red dwarfs, so scientists believe they are important places to search for planets that could support life.
One reason GJ 3378b has attracted attention is that it lies in its star’s “habitable zone.” This is the region around a star where temperatures may allow liquid water to exist on a planet’s surface.
Since every known living thing on Earth depends on water, scientists see it as one of the most important ingredients for life.
To study the planet, researchers used the Habitable-zone Planet Finder, a powerful instrument attached to the Hobby-Eberly Telescope at McDonald Observatory in Texas. Instead of looking directly at the planet, the instrument measures tiny movements of the star.
As a planet travels around its star, its gravity causes the star to wobble very slightly. By measuring this wobble, astronomers can estimate the planet’s mass and orbit.
The new observations produced an exciting surprise. When GJ 3378b was first discovered in 2024, scientists believed it had about five times the mass of Earth. The new study shows it is actually only about 2.3 times Earth’s mass.
That difference is important. Smaller “super-Earths” are more likely to be rocky planets rather than giant worlds wrapped in thick, crushing atmospheres. A rocky surface could provide a much better environment for liquid water and, potentially, life.
The researchers also found that the planet completes one orbit around its star every 21 days instead of the previously estimated 25 days. Although that seems very close to its star, the star itself is much cooler than our sun, allowing the planet to remain within the habitable zone.
However, scientists are also cautious. Being so close to a red dwarf could expose the planet to powerful radiation, which might strip away its atmosphere over time. Without an atmosphere, life as we know it would be much less likely.
Future telescopes, including the Giant Magellan Telescope, the Extremely Large Telescope and NASA’s planned Habitable Worlds Observatory, will be able to study planets like GJ 3378b in far greater detail. Scientists hope these next-generation observatories may eventually detect “biosignatures”—chemical signs that could indicate the presence of life.
For now, GJ 3378b remains one of the most intriguing nearby worlds. While there is no evidence that life exists there, the new findings suggest it could be a better place to look than scientists once imagined.
Source: University of Texas at Austin.
