⏱️ Lectura: 12 min
A Harvard-led team detected helium in the atmosphere of LHS 1140b, a rocky planet orbiting within the habitable zone of a star 48 light-years from Earth. It’s the first time an atmosphere has been confirmed on a rocky world within another star’s habitable zone, according to the study published in the journal Science.
📑 En este artículo
- TL;DR
- What Is LHS 1140b and Why This Atmosphere Matters
- How Detecting an Exoplanet Atmosphere Works
- Practical Examples: Simulating a Transit Spectrum with Python
- How to Start Exploring Exoplanet Data Yourself
- Real-World Cases: Other Candidates Under Scrutiny
- Common Mistakes and Gotchas When Interpreting These Findings
- Going Deeper: What Comes After Detecting Helium
- Comparison with Alternatives: Other Methods for Studying Exoplanets
- Frequently Asked Questions
- References
The discovery doesn’t prove there’s life: helium alone can’t sustain it. But it opens the door to studying more decisive gases on the rocky planet with the most Earth-like conditions found so far outside the solar system.
TL;DR
- You’ll understand what transit spectroscopy is and how it detects gases in the atmosphere of an exoplanet 48 light-years away.
- You’ll be able to simulate a transit light curve and a simplified transmission spectrum in Python.
- You’ll learn to use astroquery and the NASA Exoplanet Archive to explore real exoplanet data.
- You’ll understand why the helium detected on LHS 1140b doesn’t imply life, but does confirm the planet has an atmosphere.
- You’ll compare LHS 1140b with K2-18b and the TRAPPIST-1 planets to understand why their biosignatures remain unconfirmed.
- You’ll identify the most common mistakes when reading headlines about “possible life” on exoplanets.
What Is LHS 1140b and Why This Atmosphere Matters
LHS 1140b is a rocky planet orbiting a red dwarf, a star much smaller and cooler than the Sun. It’s 48 light-years away, close enough in astronomical terms for current instruments to study its atmosphere in detail.
The study’s lead author, Dr. Collin Cherubim of Harvard, described the discovery as “a big deal”: “this is the first time anyone has found an atmosphere on a rocky planet in the habitable zone of another star.” Co-author David Charbonneau, also of Harvard, added that people care about the big questions, whether we’re alone, whether there’s life beyond Earth or the solar system, and that this study reveals the first atmosphere discovered on a rocky planet within the habitable zone of a star outside the solar system.
The habitable zone is the range of distances around a star where water can exist in liquid form: not so close that it boils, not so far that it freezes. It’s colloquially known as the Goldilocks zone.
📌 Note: the name “Goldilocks zone” comes from the story of Goldilocks, the girl who looked for porridge that was neither too hot nor too cold, but “just right”: the same logic astronomers use to define a star’s habitable range.
More than 6,000 worlds have been discovered orbiting stars other than the Sun. Of all of those, only a few dozen are small and rocky like Earth, another requirement for considering habitability. But none of them had a confirmed atmosphere, until now.
How Detecting an Exoplanet Atmosphere Works
You can’t photograph the atmosphere of a planet 48 light-years away. What you can do is take advantage of the transit: the moment the planet passes directly between us and its star, blocking a tiny fraction of its light.
During that transit, part of the star’s light isn’t blocked by the planet’s solid disk, but instead grazes its atmosphere and passes through it. As it does, certain gases absorb specific wavelengths, leaving a fingerprint in the spectrum that instruments like the James Webb Space Telescope can measure with extremely high precision. This technique is called transmission spectroscopy.
It’s similar to looking at a streetlight through fog: the fog doesn’t block all the light, but it changes its color and intensity in a specific way depending on what it’s made of. By analyzing that change, you can infer the fog’s composition without touching it.
flowchart TD
A["Red dwarf star LHS 1140"] --> B["Planet LHS 1140b transits in front of the star"]
B --> C["Starlight passes through the planet's atmosphere"]
C --> D["JWST measures the transmission spectrum"]
D --> E{"Do absorption lines appear?"}
E -->|"Yes, helium"| F["Atmosphere confirmed"]
E -->|"No"| G["No detectable atmosphere"]sequenceDiagram
participant E as Star
participant P as Planet LHS 1140b
participant J as JWST
E->>J: emits background light during transit
P->>E: blocks part of the stellar disk
Note over P,E: the light grazes the atmosphere and leaves a spectral fingerprint
J->>J: splits the spectrum by wavelength
J-->>J: detects the helium absorption lineThe gas identified so far is helium, likely located in the planet’s upper atmosphere. On its own, it’s not enough to sustain life, but it confirms that LHS 1140b retains a real atmosphere, something no other rocky planet in a habitable zone had managed to demonstrate.
Practical Examples: Simulating a Transit Spectrum with Python
To understand the mechanics behind the headline, it helps to simulate the process with synthetic data. The first example generates a basic light curve, the second simulates what a helium absorption line would look like in the transmission spectrum.
import numpy as np
import matplotlib.pyplot as plt
# Simple simulation of a transit light curve
tiempo = np.linspace(-2, 2, 400) # hours relative to the center of the transit
flujo = np.ones_like(tiempo)
# The transit lasts 1 hour and reduces the flux by 0.4%
dentro_del_transito = np.abs(tiempo) < 0.5
flujo[dentro_del_transito] -= 0.004
plt.plot(tiempo, flujo)
plt.xlabel("Hours from transit center")
plt.ylabel("Relative stellar flux")
plt.title("Simulated light curve of LHS 1140b")
plt.show()This block generates a chart with a flat line that briefly drops 0.4% during the transit, the typical dip expected for a small rocky planet in front of a red dwarf. The expected result is a symmetric notch in the flux, not a spectral signal yet.
import numpy as np
# Base transit depth (solid planet, no atmosphere)
profundidad_base = 0.0040 # 0.40%
# Extra contribution from a helium atmosphere at different wavelengths
longitudes_onda_um = np.array([1.08, 1.25, 1.60, 2.06]) # microns
absorcion_helio_ppm = np.array([15, 3, 2, 4]) # extra parts per million
profundidad_total = profundidad_base + absorcion_helio_ppm * 1e-6
for lam, prof in zip(longitudes_onda_um, profundidad_total):
print(f"{lam:.2f} um -> transit depth: {prof*100:.4f}%")This second block simulates what an instrument like the JWST measures in practice: the transit depth isn’t the same at every wavelength. Near 1.08 microns, where helium absorbs most strongly, the depth rises above the solid planet’s baseline value. The expected result is a small peak at that specific wavelength compared to the others.
How to Start Exploring Exoplanet Data Yourself
You don’t need a space telescope to work with this data. The NASA Exoplanet Archive publishes the parameters of every confirmed exoplanet, including LHS 1140b, free and queryable by code.
First, set up a virtual environment and install the required libraries.
# Windows (PowerShell)
python -m venv .venv
.venv\Scripts\Activate.ps1
pip install astropy lightkurve astroquery matplotlib# macOS / Linux (bash or zsh)
python3 -m venv .venv
source .venv/bin/activate
pip install astropy lightkurve astroquery matplotlibWith the libraries installed, you can pull the planet’s real data with a single query.
from astroquery.ipac.nexsci.nasa_exoplanet_archive import NasaExoplanetArchive
tabla = NasaExoplanetArchive.query_object("LHS 1140 b")
print(tabla[["pl_name", "pl_rade", "pl_orbper", "st_dist"]])This block downloads LHS 1140b’s record live and shows its radius, orbital period, and distance to its star. The expected result is a table row with those four values pulled directly from the official archive, no need to type them by hand.
💡 Tip: you can look up the same data without installing anything, straight from your browser, on the NASA Exoplanet Archive site.
Real-World Cases: Other Candidates Under Scrutiny
LHS 1140b isn’t the only world under scrutiny in the search for life. Before this discovery, the most talked-about case was K2-18b, a sub-Neptune with a possible water-rich interior, where scientists reported signs of dimethyl sulfide, a gas associated with marine life on Earth. A NASA-led reanalysis in 2025 found that signal too weak to confirm, and showed the gas can form without biological involvement.
The seven rocky worlds of the TRAPPIST-1 system are also still being studied. NASA’s JWST ruled out an Earth-like atmosphere on TRAPPIST-1d, while data on TRAPPIST-1e remains, according to coverage of the discovery, frustratingly inconclusive.
| Planet | Type | Confirmed Atmosphere | Biosignature Search Status |
|---|---|---|---|
| LHS 1140b | Rocky, habitable zone | Yes, helium | No biosignature, only gas in upper atmosphere |
| K2-18b | Sub-Neptune with possible water-rich interior | Yes, prior to this discovery | Dimethyl sulfide reported, NASA’s 2025 reanalysis deemed the signal too weak |
| TRAPPIST-1d | Rocky, habitable zone | Earth-like atmosphere ruled out | No biosignature |
| TRAPPIST-1e | Rocky, habitable zone | Inconclusive data | Unconfirmed |
Common Mistakes and Gotchas When Interpreting These Findings
The most common mistake is reading “atmosphere detected” as synonymous with “life detected.” It isn’t. Helium is an inert gas, it doesn’t participate in biological processes, and its presence in the upper atmosphere only confirms that the planet retains one.
Another common mistake is assuming “habitable zone” means “inhabited planet,” or even “habitable” in practice. The habitable zone only defines a condition of distance and stellar temperature; many more variables (composition, magnetic field, stellar activity) are needed to know whether a planet can actually sustain life.
The third mistake, more subtle, is overinterpreting weak signals as if they were conclusive. K2-18b is the textbook example: an initially striking finding ended up downgraded once a more rigorous statistical analysis was applied.
⚠️ Heads up: detecting helium isn’t the same as detecting life. It’s an inert gas typical of the upper atmosphere; its value lies in confirming that the planet retains an atmosphere, not in indicating actual habitability.
Going Deeper: What Comes After Detecting Helium
The helium found on LHS 1140b likely originated in the planet’s upper atmosphere, possibly through hydrodynamic escape of primordial hydrogen that leaves helium behind as the heavier remnant. That mechanism differs from gases that would actually matter for life, like water vapor, carbon dioxide, methane, or oxygen, which tend to concentrate in lower atmospheric layers.
The next logical step for researchers is to point instruments with greater spectral sensitivity at those lower layers, specifically looking for those gases. It’s a process of progressive elimination: first confirm the habitable zone, then rocky size and density, then atmosphere, and only at the end, gases that could function as a biosignature.
stateDiagram-v2
[*] --> Candidate
Candidate --> HabitableZoneConfirmed: orbit measurement
HabitableZoneConfirmed --> RockyConfirmed: density calculation
RockyConfirmed --> AtmosphereConfirmed: transmission spectroscopy
AtmosphereConfirmed --> BiosignatureSearch: search for bioindicator gases
BiosignatureSearch --> [*]LHS 1140b has already cleared the first three stages of that funnel. Today, it’s the rocky habitable-zone planet that has advanced furthest in that elimination process among the more than 6,000 worlds cataloged so far.
Comparison with Alternatives: Other Methods for Studying Exoplanets
Transmission spectroscopy during transits, the technique used here, isn’t the only way to study an exoplanet. Radial velocity measures the gravitational wobble a planet induces in its star, and is mainly useful for calculating mass, not atmosphere. Direct imaging, on the other hand, attempts to photograph the planet separately from its star, something that today only works for large planets far removed from bright stars.
For a rocky planet that’s small and relatively close to its star, like LHS 1140b, transmission spectroscopy during transit is, with current technology, the only practical way to study its atmosphere. It’s also the most demanding: it requires the planet to transit from our line of sight and the atmospheric signal to not get buried in instrumental noise, something that failed for TRAPPIST-1d and remains unresolved for TRAPPIST-1e.
📖 Summary on Telegram: View summary
Your next step: run the first code block from this article in a Python notebook and modify the transit depth to see how the light curve would change if LHS 1140b had no atmosphere.
Frequently Asked Questions
What is LHS 1140b?
It’s a rocky planet orbiting within the habitable zone of a red dwarf star 48 light-years from Earth, according to the Harvard-led team.
Does the detected helium mean there’s life on LHS 1140b?
No. Helium alone can’t sustain life; the researchers themselves were clear that this finding confirms an atmosphere, not a biosignature.
What sets this finding apart from the K2-18b case?
K2-18b is a sub-Neptune, not a rocky planet, and its dimethyl sulfide signal was deemed too weak in a NASA-led reanalysis in 2025. LHS 1140b is the first confirmed case of an atmosphere on a rocky world within a habitable zone.
How did they detect the atmosphere if LHS 1140b is so far away?
With transmission spectroscopy: when the planet passes in front of its star, part of the light travels through its atmosphere and leaves a spectral fingerprint that instruments like the JWST can measure.
What method did they use to detect the helium?
The method applied is transmission spectroscopy during transits, today’s standard technique for studying rocky exoplanet atmospheres, made possible by instruments like the JWST measuring the infrared spectrum with extremely high precision.
What comes next after this discovery?
Researchers will look for deeper atmospheric gases, such as water vapor, carbon dioxide, or methane, which would actually provide evidence of real habitable conditions.
References
- BBC News: original coverage of the LHS 1140b atmosphere discovery, with statements from Collin Cherubim and David Charbonneau.
- Wikipedia: technical profile and orbital parameters of LHS 1140b.
- NASA Exoplanet Archive: public database with parameters for more than 6,000 confirmed exoplanets.
- JWST (NASA): official site of the James Webb Space Telescope and its role in exoplanet spectroscopy.
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Imagen destacada: Foto de BoliviaInteligente en Unsplash
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