Scientists detect atmosphere around rocky exoplanet LHS 1140b
Astronomers have detected the strongest evidence yet that a rocky exoplanet atmosphere exists, showing that a rocky planet in another star system has retained an atmosphere, a finding that could reshape the search for potentially habitable worlds beyond Earth.The planet, LHS 1140b, orbits a low-mass red dwarf star about 49 light-years away.
Researchers detected helium escaping from the planet’s upper atmosphere, providing evidence that the world has a gaseous envelope rather than being completely airless.The discovery, reported in a study published in Science, is important because LHS 1140b lies within its star’s habitable zone.
This is the region around a star where conditions could, depending on the planet’s atmosphere and other factors, allow liquid water to exist on the surface. The finding does not prove that the planet has life or even confirm that liquid water is present. It does, however, answer one of the central questions in the study of rocky exoplanets: can these worlds hold on to atmospheres for billions of years?
Researchers say the evidence points to a helium-rich upper atmosphere, while the composition of the deeper atmosphere remains uncertain. Future observations will be needed to determine what other gases may be present.
Why this exoplanet atmosphere discovery matters
Astronomers have found thousands of planets beyond the Solar System, but studying the atmospheres of small, rocky worlds has proved exceptionally difficult.Gas giants are easier to observe because their large atmospheres create stronger signals when they pass in front of their stars. Rocky planets are smaller, and their atmospheres can be thin, faint or completely stripped away by radiation from their host stars.
LHS 1140b is therefore a particularly valuable target. The planet is larger and more massive than Earth, with a radius of about 1.7 times Earth’s and a mass roughly 5.6 times greater. Its greater mass gives it stronger gravity, which may help it retain atmospheric material.
The latest observations offer evidence that at least some rocky planets in habitable zones can preserve atmospheres despite the harsh conditions that often threaten them.
A rocky planet in the habitable zone is not automatically habitable
The term “habitable zone” is often misunderstood. It does not mean that a planet is known to support life, has breathable air or contains oceans.It simply refers to the orbital region where temperatures could theoretically allow liquid water on the surface if the planet has suitable atmospheric conditions.
For LHS 1140b, scientists still do not know the complete composition of the atmosphere. They also have not confirmed liquid water on the surface. The planet’s climate could depend heavily on the amount and type of gases below the helium-rich upper atmosphere.That distinction is crucial.
The discovery makes LHS 1140b an important subject for habitability research, but it is not evidence that life has been found beyond Earth.
Escaping helium reveals clues about the planetary atmosphere
The researchers used the Magellan Clay Telescope at Las Campanas Observatory in Chile to study LHS 1140b as it passed in front of its star.During a planetary transit, starlight passes through the outer layers of the planet’s atmosphere.
Different chemical elements absorb specific wavelengths of light. By studying those changes, astronomers can identify gases in the planet’s upper atmosphere.The team detected a helium absorption signal associated with LHS 1140b. The helium appears to be escaping into space from the planet’s upper atmosphere.
The observations were made during approximately 6.5 hours of observations across 2024 and 2025. Helium absorption was detected in the 2024 observations but not in 2025, suggesting that atmospheric escape may vary over time.
The researchers interpret the results as evidence of an upper atmosphere dominated by helium and depleted in hydrogen. They also suggest that heavier volatile materials may remain at lower altitudes.
What the helium signal does and does not prove
The helium detection is strong evidence that LHS 1140b has atmospheric material, but it does not provide a complete picture of the planet’s atmosphere.
Scientists cannot yet say with certainty which gases dominate the lower atmosphere. Carbon dioxide, water vapour, nitrogen and other compounds have been considered in previous modelling, but the latest study does not directly confirm the presence of these gases.
The planet’s upper atmosphere may also differ greatly from the air closer to its surface. Atmospheric gases can separate and escape at different rates, especially when a planet is exposed to radiation from its star.
For that reason, detecting escaping helium is an important clue, but it should not be interpreted as a direct measurement of the atmosphere’s full chemical composition.
LHS 1140b could help explain how rocky planets retain atmospheres
The discovery also addresses a long-standing problem in exoplanet science.Red dwarf stars are smaller and cooler than the Sun, and they are the most common type of star in the Milky Way. A planet must orbit relatively close to one of these stars to receive enough energy for potentially temperate conditions.
That proximity can expose planets to powerful stellar radiation. Over long periods, radiation can heat the upper atmosphere and cause gases to escape into space.
Scientists have therefore questioned whether rocky planets orbiting red dwarfs can retain atmospheres for the billions of years that may be needed for life to develop.LHS 1140b appears to have survived that challenge, at least to some degree.
The planet’s size, mass and orbital environment may have helped it preserve atmospheric material.
A neighbouring exoplanet provides a useful comparison
LHS 1140b is not alone in its system. It has a smaller neighbouring planet, LHS 1140c.
The researchers did not detect the same helium signal from LHS 1140c, which is smaller and more heavily irradiated. The contrast between the two planets could provide an opportunity to study why some worlds retain atmospheres while others lose them.Comparisons within the same star system are particularly useful because the planets share the same host star.
Differences in mass, size and exposure to stellar radiation can then offer clues about how their atmospheres evolved.
Could LHS 1140b be a potentially habitable exoplanet?
The discovery has renewed interest in LHS 1140b as one of the most promising targets for studying potentially habitable environments beyond the Solar System.Previous research has suggested that the planet may contain substantial water or have a relatively dense atmosphere.
However, scientists have not yet confirmed the planet’s surface conditions or established whether liquid water exists there.The planet is also very different from Earth in several ways. It is more massive, larger and likely experiences a different climate.
Its host star is a red dwarf, and the planet’s close orbit could produce conditions unlike those found in our Solar System.Even so, the combination of a rocky composition, a habitable-zone orbit and evidence of an atmosphere makes LHS 1140b an unusually valuable target.
An atmosphere does not mean scientists have found life
No evidence of life has been detected on LHS 1140b.An atmosphere is one of several conditions scientists examine when assessing whether a planet could potentially support life. It can help regulate temperature and influence whether liquid water can exist, but atmospheres also occur on worlds that are completely hostile to biology.
Scientists would need much stronger evidence before claiming a biological discovery. That could include unusual combinations of atmospheric gases that are difficult to explain through known non-biological processes, although even such findings would require careful confirmation.The current discovery is therefore a step in the search for habitable environments, not a detection of extraterrestrial life.
What future observations could reveal about the rocky exoplanet atmosphere
The next stage of research will focus on determining what lies beneath the helium-rich upper atmosphere.Astronomers will need additional observations to confirm the changing helium signal and search for other atmospheric gases.
The James Webb Space Telescope and future ground-based observatories could play an important role in that work.Researchers are particularly interested in molecules that could reveal the planet’s climate, atmospheric pressure and geological history.
Detecting water vapour or other gases would help scientists test competing models of LHS 1140b’s composition.The new findings also demonstrate how astronomers are developing ways to study atmospheres on smaller planets.
If the method used for LHS 1140b can be applied to other rocky exoplanets, scientists may eventually be able to compare the atmospheres of several potentially habitable worlds.
A major step in the search for habitable worlds beyond Earth
The discovery of escaping helium from LHS 1140b marks an important moment in the study of rocky exoplanets. For years, astronomers have known that planets outside the Solar System are common, but proving that small, rocky worlds can retain atmospheres has been far more difficult.
The latest evidence suggests that LHS 1140b has not lost all of its atmospheric material, despite orbiting a red dwarf star and receiving radiation that could have stripped away its gases over time. That makes the planet a powerful laboratory for studying how atmospheres survive and evolve.The discovery does not show that LHS 1140b is another Earth.
Scientists have not confirmed liquid water, identified the full composition of its atmosphere or found any sign of life. But it has moved from being simply an interesting planet in a distant star system to one of the most important targets for future research into potentially habitable worlds.What happens next will depend on better observations.
Astronomers now need to establish whether the planet’s lower atmosphere contains water or other gases, how its atmosphere changes over time and whether its surface conditions could support liquid water.
Those answers could help scientists understand not only LHS 1140b, but also how common Earth-like atmospheric conditions may be across the Milky Way.
Curated news reports, in-depth analysis, and special features by India’s Opinion editorial team.
