Planetary-Scale Optical Modulation as a Framework for Interstellar Communication

This work presents a conceptual framework for interstellar communication based on planetary-scale optical modulation of stellar and artificial light sources. The system encodes information through time-varying reflectance and emission, producing structured signals detectable at interstellar distances. The architecture is grounded in established physical principles and does not involve faster-than-light communication. Instead, it emphasizes persistence, robustness, and interpretability over bandwidth. Included are a system model, order-of-magnitude analysis, numerical estimates, and receiver-side decoding considerations. This work is intended as a forward-looking contribution to technosignature detection and interstellar signaling strategies.