Description des 6 paramètres orbitaux

orbit.tex

\documentclass[border=10pt,varwidth]{standalone}

\usepackage[francais]{babel}
\usepackage[dvipsnames]{xcolor}

\usepackage{fontspec}
\usepackage{unicode-math}
\usepackage{tikz}

\usetikzlibrary{intersections}

\setmainfont{Linux Libertine O}
\setmathfont{Asana Math}

\begin{document}

\begin{figure}
\begin{center}
    \begin{tikzpicture}[scale=1.5]
        \draw[name path=e1, gray!10, fill=gray!10] (0,0) ellipse (2 and 1);
        \node[] at (-60:2 and 1) (i1) {};
        \begin{scope}[rotate=45, xshift=1]
            \draw[name path=e2] (0,0) ellipse (2 and 1);
            \node[] at (-75:2 and 1) (i2) {};
            \node[circle,shading=ball,ball color=BrickRed]
            at (60:2 and 1) (i3) {};
            \node at (180:2 and 1) {\em plan de l'orbite};
            \node[BrickRed, anchor=east, left of=i3, node distance=15mm]
            {corps céleste};
            \node at (60:.6 and .3) (anom) {};
            \draw[dashed] (0,0) to (2,0);
            \node  at (.5,0) (stop) {};
            \node[draw, circle, fill=black, inner sep=0pt, minimum size=1mm]
            at (0:2 and 1) (per) {};
            \node[anchor=south west] at (per) {périgée};
        \end{scope}
        \draw[->, thick, OliveGreen] (i1) to [bend right]
        node[right] {$i$} (i2);
        \path [name intersections={of=e1 and e2}];
        \draw [dashed] (0,0) -- (intersection-4);
        \node[circle, fill=black, inner sep=0pt, minimum size=1mm] at
        (intersection-4) {};
        \node[anchor=north west] at (intersection-4) {nœud ascendant};
        \draw [BrickRed] (0,0) -- (i3);
        \draw [->] (0,0) -- (2.1,0) node[right] (gamma) {$\gamma$};
        \draw[->, MidnightBlue] (.25,0) arc
        [start angle=0, end angle=278, x radius=.25, y radius=.2]
        node (start) {} node[below left] {$\Omega$};
        \draw[->] (start) to[bend right] (stop) node[below right] {$\omega$};
        \draw[->, BrickRed] (stop) to[bend right] (anom)
        node[above right] {$\upsilon$};
        \path node[below of=gamma,node distance=3mm,anchor=east] {point vernal};
        \node[gray!70, anchor=west] at (intersection-3)
        {\em plan de l'équateur};
    \end{tikzpicture}
\end{center}

\caption{Représentation des paramètres orbitaux: inclinaison $i$, longitude du
nœud ascendant $\Omega$, argument du périgée $\omega$ et anomalie vraie
$\upsilon$}

\end{figure}

\end{document}