Plate Nº 91 · recorded October 10, 2026
Space & AstronomyReported finding
Helium Leak Hints at Second Atmosphere on Exoplanet LHS 1140b
Astronomers report helium escaping from LHS 1140b, a possibly rocky habitable-zone world — only the second hint of an atmosphere around an Earth-like planet.
By James Calloway3 min read686 words
In brief
- LHS 1140b orbits its red dwarf star every 24.7 days and is about 1.7 times Earth's size with just over 5 Earth masses.
- The helium detection is only the second hint of an atmosphere around a remotely Earth-like planet, after Gliese 1214b.
- A second observation within the same study failed to detect the helium, leaving the result tenuous.
- The planet's temperature could range from 0°C to 100°C, or plunge to -90°C depending on untested assumptions.
- The study, led by Collin Cherubim et al., was published in Science (2026), DOI: 10.1126/science.aea9708.
Astronomers have reported helium gas escaping from the atmosphere of LHS 1140b, a potentially rocky planet orbiting in the habitable zone of a nearby red dwarf star — only the second time scientists have captured even a hint of an atmosphere around a remotely Earth-like world. The finding, published in Science by Collin Cherubim and colleagues, moved this exoplanet from scientific journals into mainstream headlines this summer.
The signal is faint, and one of the study's own follow-up observations failed to see the helium again. Even so, researchers say it represents real, if incremental, progress toward reading the atmospheres of potentially habitable planets.
What makes helium exciting?
Earlier observations of LHS 1140b with the James Webb Space Telescope ruled out a hydrogen-rich "primary" atmosphere — the kind thought to form alongside young planets and then quickly bleed away into space. Astronomers believe all rocky planets briefly carry such an atmosphere and lose it soon after forming.
The helium detection may instead point to a "secondary" atmosphere: one that persists around a planet and that astronomers can actually study. Earth offers the best-known example. Our secondary atmosphere has lasted billions of years, and its chemical balance reflects the combined influence of geology, chemistry and, ultimately, life.
Where is this planet, and what is it?
LHS 1140b sits in the constellation Cetus, next to the recognizable "W" of Cassiopeia. Don't bother squinting, though: its parent star appears roughly 10,000 times fainter than the dimmest star visible to the naked eye.
The planet orbits a red dwarf about one-fifth the Sun's mass but some 300 times fainter. Its star dims in a regular dip every 24.7 days. From the size of that dip, the discovery team — which found the planet in 2017 — calculated a diameter 1.7 times Earth's. Later measurements put its mass at just over five Earth masses.
That leaves astronomers with a labeling problem. Is LHS 1140b a rocky "super-Earth" or a small gaseous "mini-Neptune"? Nobody knows, largely because our solar system offers no comparison: the next planet up in mass from Earth is Uranus at 14 Earth masses, then Neptune at 17. Sub-Neptunian worlds like this one appear to be the most common type of planet in the galaxy, making this blind spot in planetary physics a pressing one.
Could it host life?
LHS 1140b lies in its star's habitable zone, meaning its surface temperature could fall between 0°C (32°F) and 100°C (212°F) — the range where liquid water, and possibly life, could exist.
The temperature estimates carry big caveats. If the planet absorbs all incoming stellar radiation, it settles at an equilibrium of -30°C (-22°F). A more realistic mathematical treatment pushes it as low as -90°C (-130°F), comparable to present-day Mars. A thick atmosphere with a strong greenhouse effect could still warm it, but the calculations rest on significant, untested assumptions.
How solid is the result?
Not very — yet. This is only the second hint of an atmosphere around an Earth-like planet; the first came around Gliese 1214b. A second observation of LHS 1140b within the same study did not show helium, and researchers cannot yet explain why.
The detection still matters. A rocky, Earth-like planet with a detectable atmosphere in a habitable zone would be a major discovery, whatever its star's dimness. And as the article's author notes, the result came from years of dedicated effort by the science team — effort that deserves recognition, respect and future funding.
When will we know if a planet hosts life?
Detecting life itself will require patience. Which biogenic molecules — perhaps oxygen, or methane, as in Earth's own atmosphere — will provide an unambiguous "smoking gun" remains an open question.
The likeliest path forward is volume: observing thousands of exoplanet atmospheres rather than one or two, letting nature teach us the rules by which planetary atmospheres work. That work has only just begun. But if a journey of a thousand planets starts with a single step, LHS 1140b just made it two.
via Phys.org Space & Astronomy (Source)
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Staff writer covering marketplaces and e-commerce at SciBeat.
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