On the Spin-axis Dynamics of a Moonless Earth
- Creators
- Li, Gongjie
- Batygin, Konstantin
Abstract
The variation of a planet's obliquity is influenced by the existence of satellites with a high mass ratio. For instance, Earth's obliquity is stabilized by the Moon and would undergo chaotic variations in the Moon's absence. In turn, such variations can lead to large-scale changes in the atmospheric circulation, rendering spin-axis dynamics a central issue for understanding climate. The relevant quantity for dynamically forced climate change is the rate of chaotic diffusion. Accordingly, here we re-examine the spin-axis evolution of a Moonless Earth within the context of a simplified perturbative framework. We present analytical estimates of the characteristic Lyapunov coefficient as well as the chaotic diffusion rate and demonstrate that even in absence of the Moon, the stochastic change in Earth's obliquity is sufficiently slow to not preclude long-term habitability. Our calculations are consistent with published numerical experiments and illustrate the putative system's underlying dynamical structure in a simple and intuitive manner.
Additional Information
© 2014 The American Astronomical Society. Received 2013 November 20; accepted 2014 April 29; published 2014 July 7. We thank Jacques Laskar for helpful comments.Attached Files
Published - Li_2014_ApJ_790_69.pdf
Accepted Version - 1404.7505.pdf
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Additional details
- Eprint ID
- 94375
- Resolver ID
- CaltechAUTHORS:20190402-141541917
- Created
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2019-04-02Created from EPrint's datestamp field
- Updated
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2021-11-16Created from EPrint's last_modified field
- Caltech groups
- Division of Geological and Planetary Sciences