About this Research Topic
Since antiquity, the movements of the planets of the solar system attracted the attention of astronomers because the orbital periods appeared to be related by simple harmonic proportions, resonances and/or commensurabilities (known as "the music of the spheres"); for example, 5 revolutions of Jupiter approximately corresponds to 2 revolutions of Saturn. Also, lunar systems present similar properties; for example, the inner three moons of Jupiter, Io, Europa and Ganymede, are locked in a 4:2:1 orbital resonance. Such properties suggested that the formation of planetary systems can be characterized by gravitational self-organization and synchronization processes. In the end, gravitational couplings can produce long-term quasi-stable planetary orbits that appear tuned to each other. Similar characteristics are also being discovered in exoplanetary systems (e.g., Trappist-1 solar system). Even more intriguingly, the planetary harmonics of our solar system have been found to be spectrally coherent with several activity cycles of the Sun and of the Earth's climate system. The physical explanation of these phenomena is still open.
We need to better understand the phenomenology and the physical processes that produce the gravitational self-organization of planetary and lunar systems and, in particular, of our solar system. Moreover, solar-type stars could exhibit variabilities which are coupled with the planetary orbits. For example, the Sun has the 11-year Schwabe cycle, the 22-year Hale cycle, and many other shorter and longer activity cycles ranging from a month to thousands of years like the "Gleissberg cycle" (about 85 years), the "Suess-de Vries cycle" (about 200 years), the quasi millennial "Eddy cycle", and the "Bray-Hallstatt cycle" (about 2300 years). The precise physical origin of these solar cycles is still debated, but recent literature has strengthened the correlation with planetary harmonics. The shorter solar cycles are easily detected in the total solar irradiance, sunspot records, etc., while the longer ones are testified by geophysical records like the cosmogenic radionuclide records (C14 and Be10) and also in the Earth's climatic records. Thus, solar systems could manifest similar highly synchronized dynamics also driving solar and climate cycles. The goal of this Research Topic is to collect the observational evidences and the models proposed in the literature, and trigger an interdisciplinary discussion on these topics.
This Research Topic aims to address the problem of the self-organization mechanisms within planetary systems and to cast light on whether and how the planetary harmonics could tune the quasi-periodic activity cycles observed in the Sun and, as a consequence, in the Earth's climate. The Research Topic welcomes empirical and theoretical studies and reviews, on themes including:
1. Empirical evidences and models describing the planetary and lunar systems self-organization and coupling processes;
2. Empirical evidences and models explaining why some solar and climate activity cycles appear synchronized with the planetary orbital motions.
We need to better understand the phenomenology and the physical processes that produce the gravitational self-organization of planetary and lunar systems and, in particular, of our solar system. Moreover, solar-type stars could exhibit variabilities which are coupled with the planetary orbits. For example, the Sun has the 11-year Schwabe cycle, the 22-year Hale cycle, and many other shorter and longer activity cycles ranging from a month to thousands of years like the "Gleissberg cycle" (about 85 years), the "Suess-de Vries cycle" (about 200 years), the quasi millennial "Eddy cycle", and the "Bray-Hallstatt cycle" (about 2300 years). The precise physical origin of these solar cycles is still debated, but recent literature has strengthened the correlation with planetary harmonics. The shorter solar cycles are easily detected in the total solar irradiance, sunspot records, etc., while the longer ones are testified by geophysical records like the cosmogenic radionuclide records (C14 and Be10) and also in the Earth's climatic records. Thus, solar systems could manifest similar highly synchronized dynamics also driving solar and climate cycles. The goal of this Research Topic is to collect the observational evidences and the models proposed in the literature, and trigger an interdisciplinary discussion on these topics.
This Research Topic aims to address the problem of the self-organization mechanisms within planetary systems and to cast light on whether and how the planetary harmonics could tune the quasi-periodic activity cycles observed in the Sun and, as a consequence, in the Earth's climate. The Research Topic welcomes empirical and theoretical studies and reviews, on themes including:
1. Empirical evidences and models describing the planetary and lunar systems self-organization and coupling processes;
2. Empirical evidences and models explaining why some solar and climate activity cycles appear synchronized with the planetary orbital motions.
Keywords: Gravitational self-organization of planetary and lunar systems; Orbital resonances and commensurabilities; Planets-star synchronization; Solar activity cycles; Climate cycles; Resonant exoplanetary systems.
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