\documentstyle{article}
\title{Large Scale Chaos   and   Marginal Stability \\ in  the    Solar
System}
\author{Jacques Laskar\\
Astronomie et Syst\`emes Dynamiques,\\
Bureau des Longitudes, 3 rue Mazarine, 75006 Paris, France
\\
E-mail:  laskar@imcce.fr }
\date{}

\begin{document}
\maketitle

Large scale chaos is present everywhere in the solar
system.  All the inner
planets probably experienced large scale chaotic behavior for
their obliquities during their history. The Earth obliquity
is presently stable only
because of the presence of the Moon, and the tilt of Mars
undergoes large chaotic variations from $0^\circ$ to about
$60^\circ$. On billion years time scale, the orbits of the
planets themselves present strong chaotic variations which can lead
to the escape of Mercury or collision with Venus in less
than 3.5 Gyr. The organization of the planets in the solar
system thus seems to be strongly related to this chaotic
evolution, reaching at all time a state of marginal
stability, that is practical stability on a time-scale
comparable to its age.

\end{document}

