Наклон оси Земли

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Наклон оси вращения Земли к плоскости орбиты Земли вокруг Солнца составляет около 23°. Мог ли такой наклон возникнуть без Мегаимпакта?

В 1989 г. французский ученый Jacques Laskar показал, что ошибка в определении положения Земли на 15 метров делает невозможным предсказание положения Земли на орбите через 100 млн. лет. Эти результаты были в дальнейшем подтверждены другими учеными, тем самым была доказана хаотичность динамики Солнечной системы. В работах 1993 г. Jacques Laskar показал, что наклон оси вращения внутренних планет в результате их гравитационного взаимодействия меняется хаотически, и изначально мог отсутствовать. Наибольшая нестабильность возникает для Марса, на Меркурий и Венеру некоторое стабилизирующее воздействие оказывают приливные силы Солнца, на Землю — влияние Луны. Однако, по мере удаления Луны от Земли хаотичность может возрастать, приводя к изменению угла наклона вплоть до 85°. В работе 2009 г. Jacques Laskar показал, что резонансное взаимодействие Меркурия с Юпитером может привести через примерно 3 миллиарда лет к столь значительному росту эксцентриситета орбиты Меркурия, что это может повлечь за собой столкновение внутренних планет Солнечной системы.

Сказанное свидетельствует о том, что на протяжении миллиардов лет, прошедших с образования системы Земля-Луна, гравитационное воздействие других планет вполне могло изменить наклон оси Земли до наблюдающегося в настоящее время значения.

Википедия

Ученые

  • Jacques Laskar, Astronomie et Systèmes Dynamiques, IMCCE, Observatoire de Paris, France. Homepage
  • Jack Wisdom, Prof. of Planetary Science, Massachusetts Institute of Technology, USA. Wikipedia, homepage.

Литература

  • Laskar, J.; Gastineau, M. (2009). Existence of collisional trajectories of Mercury, Mars and Venus with the Earth. Nature 459. [1]
We report numerical simulations of the evolution of the Solar System over 5 Gyr, including contributions from the Moon and general relativity. In a set of 2,501 orbits with initial conditions that are in agreement with our present knowledge of the parameters of the Solar System, we found, as in previous studies2, that one per cent of the solutions lead to a large increase in Mercury’s eccentricity — an increase large enough to allow collisions with Venus or the Sun. More surprisingly, in one of these high-eccentricity solutions, a subsequent decrease in Mercury’s eccentricity induces a transfer of angular momentum from the giant planets that destabilizes all the terrestrial planets ~3.34 Gyr from now, with possible collisions of Mercury, Mars or Venus with the Earth.
  • J. Touma and J. Wisdom. The Chaotic Obliquity of Mars. 1993, Science 259, 1294. Download pdf: 962 Kb
The discovery (by Laskar, 1989, 1990) that the evolution of the solar system is chaotic, made in a numerical integration of the averaged secular approximation of the equations of motions for the planets, was confirmed by Sussman and Wisdom (1992) by direct numerical integration of the whole solar system. This paper presents results of direct integrations of the rotation of Mars in the chaotically evolved planetary system, made using the same model as that used by Sussman and Wisdom. The numerical integration shows that the obliquity of Mars undergoes large chaotic variations, which occur as the system evolves in the chaotic zone associated with a secular spin-orbit resonance. [2], [3].
  • Jacques Laskar, F.Joutel, and P. Robutel, Stabilization of the Earth's Obliquity by the Moon, Nature 361 (1993), pages 615-617.
According to Milankovitch theory, the ice ages are related to variations of insolation in northern latitudes resulting from changes in the Earth's orbital and orientation parameters (precession, eccentricity and obliquity). Here we investigate the stability of the Earth's orientation for all possible values of the initial obliquity, by integrating the equations of precession of the Earth. We find a large chaotic zone which extends from 60° to 90° in obliquity. In its present state, the Earth avoids this chaotic zone and its obliquity is essentially stable, exhibiting only small variations of ± 1.3° around the mean value of 23.3°. But if the Moon were not present, the torque exerted on the Earth would be smaller, and the chaotic zone would then extend from nearly 0° up to about 85°. Thus, had the planet not acquired the Moon, large variations in obliquity resulting from its chaotic behaviour might have driven dramatic changes in climate. In this sense one might consider the Moon to act as a potential climate regulator for the Earth. [4], [5]
  • Jacques Laskar, and P. Robutel, The Chaotic Obliquity of the Planets, Nature 361 (1993), pages 608-612. [6]
The obliquity or spin-axis orientation of the inner or terrestrial planets, Mercury, Venus, Earth and Mars, has undergone chaotic variations in the planets' histories and Mars is still experiencing variations. Therefore, their obliquities cannot be considered primordial since they could have started with almost a zero obliquity that changed during the chaotic variation caused by their primordial spin rate. Mercury and Venus' obliquities have stabilized because of tidal dissipation while the Moon may have had the same effect on the Earth. [7]
  • ЗЕМЛЯ: МЕСТО ДЛЯ ЖИЗНИ
    • William R. Ward, Comments on the Long-Term Stability of the Earth's Obliquity, Icarus 50 (1982), pages 444-448.
    • Carl D. Murray, Seasoned Travelers, Nature 361 (1993), pages 586-587.
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