Astronomers have detected what they say is the first confirmed atmosphere surrounding a rocky exoplanet in the habitable zone of another star, marking a major milestone in the search for potentially life-supporting worlds beyond our solar system.
The planet, known as LHS 1140 b, lies about 48 light-years from Earth and is estimated to be nearly five billion years old—slightly older than Earth itself. Researchers found evidence that the planet is continuously replenishing its atmosphere after detecting helium escaping into space, suggesting it has retained a stable gaseous envelope over billions of years.
The findings, published in the journal Science, could reshape scientists’ understanding of how rocky planets evolve and improve the prospects of finding habitable environments elsewhere in the galaxy.
What Is LHS 1140 b?
LHS 1140 b is a rocky exoplanet orbiting a small red dwarf star approximately 48 light-years from Earth.
The planet was first discovered in 2016 and has attracted scientific interest because it lies within its star’s habitable zone—the region where temperatures could allow liquid water to exist under the right atmospheric conditions.
Researchers estimate that the planet is nearly five billion years old, making it slightly older than Earth, which formed about 4.5 billion years ago.
Because one side of the planet is thought to permanently face its star while the other remains in darkness, scientists have sometimes referred to it as an “eyeball Earth.” In such worlds, models suggest the sunlit side could contain a warm region surrounded by colder areas, resembling the appearance of an eye.
Why Is This Discovery So Important?
Until now, astronomers had identified thousands of exoplanets, including many rocky worlds similar in size to Earth.
However, confirming the presence of a stable atmosphere around a rocky exoplanet has proved extremely challenging.
According to the research team, LHS 1140 b is the first rocky planet in another star’s habitable zone where scientists have detected compelling evidence of an atmosphere.
A stable atmosphere is considered one of the essential ingredients for maintaining surface conditions that could potentially support life as we know it.
It can regulate temperature, shield a planet from harmful radiation, and help sustain liquid water.
How Did Scientists Detect the Atmosphere?
Researchers observed helium escaping from the planet using the Magellan Clay Telescope at Las Campanas Observatory in Chile.
At first glance, detecting gas leaking into space might seem like evidence that the atmosphere is disappearing.
Instead, scientists reached the opposite conclusion.
Because helium is a lightweight gas that gradually escapes a planet’s gravity, its continued presence suggests the atmosphere is constantly being replenished. If that were not happening, the helium would likely have been lost long ago over the planet’s multi-billion-year history.
The observations matched theoretical models predicting that LHS 1140 b possesses a helium-rich upper atmosphere.
Why Does Escaping Helium Matter?
Helium is one of the lightest elements in the universe, making it relatively easy for a planet to lose over time.
Finding helium escaping from LHS 1140 b indicates that atmospheric processes are still active.
Researchers believe this ongoing replenishment is strong evidence that the planet has maintained an atmosphere for billions of years despite gradual gas loss into space.
That makes LHS 1140 b unusual among known rocky exoplanets, many of which appear to have lost their atmospheres entirely.
Could LHS 1140 b Support Life?
The discovery does not mean life exists on the planet.
Scientists have only confirmed evidence of an atmosphere—not its complete chemical composition or whether liquid water exists on the surface.
Future observations will focus on determining:
- The gases that make up the atmosphere.
- Whether water vapor is present.
- If surface oceans exist.
- Whether temperatures remain suitable for liquid water.
- Signs of potential biological activity.
These questions will require more detailed observations using current and future space telescopes.
What About the Other Planet in the System?
LHS 1140 also hosts another known planet called LHS 1140 c.
Unlike LHS 1140 b, the second planet orbits outside the system’s habitable zone.
According to the researchers, observations have not revealed evidence of an atmosphere surrounding LHS 1140 c, highlighting how different planets within the same planetary system can evolve in very different ways.
Why This Matters for the Search for Life
More than 6,000 exoplanets have now been discovered, but identifying potentially habitable worlds requires much more than simply finding rocky planets.
Scientists also need evidence that those planets have retained stable atmospheres over geological timescales.
The discovery of atmospheric helium on LHS 1140 b suggests that some rocky planets orbiting red dwarf stars may be able to preserve atmospheres for billions of years.
That significantly expands the range of worlds astronomers may consider promising targets in the search for extraterrestrial life.
The Bottom Line
The discovery of an atmosphere around LHS 1140 b marks an important advance in exoplanet research. By detecting helium escaping into space, astronomers have gathered strong evidence that this rocky world has maintained—and continues to replenish—its atmosphere despite being nearly five billion years old.
While the findings do not demonstrate that the planet is inhabited, they strengthen the possibility that some rocky planets beyond our solar system could possess the long-term stability needed to support life. Future observations will aim to determine whether LHS 1140 b also has water, oceans, or other characteristics associated with habitable environments.
TL;DR
- Astronomers have detected an atmosphere on the rocky exoplanet LHS 1140 b.
- The discovery marks the first confirmed atmosphere around a rocky planet in the habitable zone of another star, according to the researchers.
- Scientists detected helium escaping from the planet, indicating its atmosphere is continuously replenished.
- LHS 1140 b is located 48 light-years away and is nearly five billion years old.
- The discovery strengthens hopes that some rocky exoplanets may retain conditions suitable for life.
