2,41 hours. That's exactly how long a day lasts on SIMP 0136 — a lonely planet-like object 6,1 parsecs away. That's twice as far as Proxima Centauri. Its mass ranges from 12,7 to 17,8 Jupiter masses, placing it on the boundary between planet and star. The James Webb Space Telescope observed it for 1,2 rotations, capturing spectra every few minutes. Thousands of wavelengths — like threads in a huge tangle. Each thread shimmers and flickers as the distant world rotates. Untangling this knot was principal component analysis (PCA). It finds the directions along which the data vary the most. And it found just two such directions.

The first component is almost gray: it uniformly brightens or dims the light at all wavelengths. That's how the overall effective temperature behaves — it jumps between 900 and 1400 kelvins. The second component is chromatic: it alters absorption bands of water, carbon monoxide, methane, and carbon dioxide differently. This is the cloud system at work — dust particles that rise to the upper layers or sink deep.

If you plot the two components, time traces a closed loop. Not a chaotic blob, but a neat triangle. Each cycle lasts exactly 2,41 hours. The three vertices are three extreme states: hot and clear; cold with high clouds; and intermediate. In one rotation, the atmosphere cycles through all three.

Comparison with a grid of 9000 self-consistent models showed that the same two factors explain 79,9% of the theoretical variability. This is not just a mathematical trick: it's real physics. Clouds condense, heat redistributes. And it all fits into two numbers.

Thus the tangled skein of the spectrum revealed a simple picture. The weather on SIMP 0136 is not chaos, but a dance with a clear rhythm. And the key to it has been found.