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Why do we see the man in the Moon?

Aharonson, Oded and Goldreich, Peter and Sari, Re'em (2012) Why do we see the man in the Moon? Icarus, 219 (1). pp. 241-243. ISSN 0019-1035.

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Numerical simulations and analysis show that the Moon locks into resonance with a statistical preference of facing either the current near-side or far-side toward Earth. The near-side is largely covered by dense, topographically low, dark mare basalts, the pattern of which to some, resembles the image of a man’s face. Although the Moon is locked in this configuration at present, the opposite one, with the current far-side facing Earth, is of lower potential energy and hence might be naively expected. Instead, we find that the probability of selecting each configuration depends upon the ratio of the asymmetry of the potential energy maxima, dominated by the octupole moment of the Moon, to the energy dissipated per tidal cycle within the Moon. If this ratio is small, the two configurations are equally likely. Otherwise, interesting dynamical behavior ensues. In the Moon’s present orbit, with the best-estimated geophysical parameters and dissipation parameter Q = 35, trapping into the current higher-energy configuration is preferred. With Q = 100 in analogy with the solid Earth, the current configuration is nearly certain. The ratio of energies and corresponding probabilities were different in the past. Relative crater counts on the leading and trailing faces indicate an impact may have unlocked the Moon before it settled into the present configuration. Our analysis constrains the geophysical parameters at the time of the last such event.

Item Type:Article
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URLURL TypeDescription
Aharonson, Oded0000-0001-9930-2495
Sari, Re'em0000-0002-1084-3656
Additional Information:© 2012 Elsevier. Received 12 July 2011. Revised 8 February 2012. Accepted 17 February 2012. Available online 27 February 2012. O.A. thanks Bruce Bills for introducing him to this question, Mark Wieczorek for helpful discussions, and two anonymous reviewers for their constructive reviews. We are thankful for the support of the Lunar Reconnaissance Orbiter Project (Grant # NNX08AZ54G).
Funding AgencyGrant Number
Subject Keywords:Moon; Moon, Interior; Satellites, Dynamics
Issue or Number:1
Record Number:CaltechAUTHORS:20120817-105459244
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Official Citation:Oded Aharonson, Peter Goldreich, Re’em Sari, Why do we see the man in the Moon?, Icarus, Volume 219, Issue 1, May 2012, Pages 241-243, ISSN 0019-1035, 10.1016/j.icarus.2012.02.019. (
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:33291
Deposited By: Ruth Sustaita
Deposited On:17 Aug 2012 18:05
Last Modified:03 Mar 2020 13:01

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