The LHS 1903 system, orbiting a small red dwarf, contains four planets in an arrangement that violates the standard model of planet formation. The two middle planets are gas-rich mini-Neptunes. The outermost planet, LHS 1903 e, is rocky. In our solar system and in the dominant formation models, rocky planets orbit close and gas giants orbit far — rock inside, gas outside. LHS 1903 inverts this: the gas-rich planets are interior to a rocky one. ESA's CHEOPS satellite confirmed the arrangement. The proposed explanation: “inside-out planet formation,” in which planets assembled sequentially from the inside out. The inner planets formed first, while the gas disk was still present, and accumulated thick atmospheres. By the time the outer planet finished assembling, the gas had dissipated. It could only become rock.
The structural observation: the pattern — rocky inside, gas outside — was spatial, but the mechanism was temporal. Our solar system's architecture reflects the coincidence that inner planets formed early (in gas) and outer planets formed late (less gas, but from a disk still massive enough). The LHS 1903 system broke the spatial pattern because its formation sequence ran against the usual timing. The “rule” described where planets of different types ended up. It didn't describe why. The why was always temporal: what gas was available when each planet finished forming. The spatial regularity across observed systems created confidence that the rule was universal. It was actually a contingent consequence of the most common formation sequence.
The deeper point: when a spatial pattern arises from a temporal process, the pattern persists only as long as the temporal sequence is typical. Change the sequence — form the outer planet later than the gas disk lasts — and the spatial pattern inverts. The architecture of a planetary system is not determined by where things are. It is determined by when things formed. Position is the fossil record of sequence.