\documentclass{article}
\usepackage{pstricks}
\SpecialCoor
\usepackage{pst-grad}

\parindent=0pt
\pagestyle{empty}
\begin{document}

\begin{pspicture}(-5,-2.75)(5,5.5)
%\psgrid[griddots=10,gridlabels=7pt,subgriddiv=0]
% dicke Kugeln
\pscircle[fillstyle=gradient,gradbegin=white,%
		gradend=black,gradmidpoint=0,gradangle=90](-4,-2){0.75}
\pscircle[fillstyle=gradient,gradbegin=white,%
		gradend=black,gradmidpoint=0,gradangle=90](4,2){0.75}
\pscircle[linestyle=dashed](-4,2){0.75}
\pscircle[linestyle=dashed](4,-2){0.75}
% kleine Kugeln
\psline[linewidth=0.5pt](-4,-0.75)(4,0.75)
\psline[linewidth=0.5pt,linestyle=dashed](-4,0.75)(4,-0.75)
\psline[linewidth=2pt](-0.5,-0.1)(0.5,0.1)
\psline[linewidth=2pt](-0.5,0.1)(0.5,-0.1)
\pscircle[fillstyle=gradient,gradbegin=white,%
		gradend=black,gradmidpoint=0,gradangle=90](-4,-0.75){0.2}
\pscircle[fillstyle=gradient,gradbegin=white,%
		gradend=black,gradmidpoint=0,gradangle=90](4,0.75){0.2}
\pscircle[linestyle=dashed](-4,0.75){0.2}
\pscircle[linestyle=dashed](4,-0.75){0.2}
\psline[linewidth=0.2pt](-5.2,-0.75)(-4.8,-0.75)
\psline[linewidth=0.2pt](-5.2,-2)(-4.8,-2)
\psline[linewidth=0.2pt,arrowscale=2]{<->}(-5,-2)(-5,-0.75)
\uput[180](-5,-1.4){r}
\psline[linewidth=0.2pt,arrowscale=2]{<->}(-4,-1.1)(0,-1.1)
\psline[linewidth=0.2pt](0,-0.9)(0,-1.3)
\uput[-90](-2,-1.1){a}
\psarc[linewidth=0.2pt]{<->}(0,0){4.5}{-11}{11}
\uput[0](4.5,0){$\varphi$}
\psline[linewidth=0.2pt,linecolor=red,arrowscale=2]{->}(-3,5)(0,0)(5,3.8)
\psline[linewidth=0.2pt,linecolor=red,arrowscale=2]{->}(0.8,5)
\psarc[linewidth=0.2pt,arrowscale=2]{<->}(0,0){4.5}{37}{81}
\uput[0](4;60){$2\varphi$}
\psline[linewidth=0.2pt,arrowscale=2]{<->}(0.8,5)(5,3.8)
\uput[45](3,4.5){s}
\rput{-57}(6;124){\psframe[fillstyle=gradient,gradbegin=white,%
		gradend=red,gradmidpoint=0,gradangle=90](0,0)(1.5,0.5)}
\end{pspicture}

\end{document}
