Resonant Hierarchies in Astrophysical and Biological Systems:\\ From Planetary Electromagnetic Cavities to Pulsar Metronomes\\ (With a Coherence-Ladder Interpretation

abstract Claims that ``Earth resonates at 432 Hz'' circulate widely in cultural and musical contexts, but they do not correspond to a known geophysical fundamental mode. In contrast, multiple resonance phenomena across celestial bodies are directly observed and quantitatively characterized: (i) global extremely-low-frequency (ELF) electromagnetic standing waves in the Earth--ionosphere cavity (Schumann resonances) with a fundamental near 7.83 Hz; (ii) helioseismic pressure-mode oscillations of the Sun clustered in the millihertz regime, including the canonical ``five-minute'' oscillations; and (iii) neutron-star spin frequencies extending into the human-audible band, with the fastest known millisecond pulsars rotating at $\sim$716 Hz. We synthesize these into a \emph{resonance ladder} spanning many orders of magnitude and propose a coherence-centric interpretive layer: larger, weakly constrained systems preferentially support lower-frequency global modes, whereas compact, strongly constrained systems can sustain higher-frequency coherent timing. We further discuss how biological oscillators (EEG bands from delta through gamma) occupy an intermediate window that may be entrainable by natural environmental rhythms without implying that musical tuning standards are geophysical constants. We conclude with testable predictions and measurement protocols that distinguish (a) physically defined resonances (electromagnetic cavity, elastic normal modes, stellar oscillations, rotational coherence) from (b) culturally selected frequencies.