Cambridge reported a tentative DMS or DMDS signal on K2-18b
Using a different Webb instrument and wavelength range, a Cambridge-led team reported a signal consistent with dimethyl sulfide, dimethyl disulfide, or both in K2-18b's atmosphere. The result reached three-sigma statistical significance, short of the conventional five-sigma discovery threshold, and the molecules could have an unknown non-biological source. The researchers said more observations and chemical testing were needed; the result was not a detection of life.
The record ends here. Everything below this line is invented.
What if a chemical hint made a distant planet feel inhabited before anyone could prove it?
Part one
The Three-Sigma Sea
Mina began each class by darkening the ceiling. The planetarium's new dome could lay Webb spectra over the stars in real time, but she still made her students wait through the quiet part: the blank strip where a molecule might be, or might not.
For years, every child in her district had been taught the phrase possible biosignature. The signal from K2-18b had grown stronger with follow-up observations, but the instrument could not yet tell whether the overlapping bands belonged to one sulfur molecule or another. Her daughter, who had helped build the dome, wanted the school to name the planet's ocean. The district's trustees wanted a celebration before the next budget vote. Mina had promised neither.
That morning the new reduction finished before the first bell. A second line had appeared beside the old one, same direction, different depth. If she showed it, the students would call the planet alive. If she hid it, they would learn that doubt meant silence. Mina opened the dome and placed both spectra above the winter stars. Her daughter took the pointer and touched the narrow space between the two peaks. The display began to hum.
What’s real
- The Cambridge-led result was at three-sigma significance.
- The signal was consistent with DMS, DMDS, or both.
- The researchers said non-biological chemistry remained possible.
What’s invented
- Mina, her daughter, and the planetarium are fictional.
- The follow-up spectrum and school debate are invented.
- No life has been confirmed on K2-18b.
Part two: Between the Peaks
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Filed under space, exoplanets, biosignature, astronomy.