verbatimtex %&latex \documentclass{article} \usepackage{fourier} \begin{document} etexbeginfig(1); % excentricité, demi-grand axe, demi-petit axe numeric e,a,b; e = 0.4; a = 100; b = a * sqrt(1 - e * e) ; path cp,el; % cercle principal cp = fullcircle scaled 2a; % ellipse el = fullcircle xscaled 2a yscaled 2b; pair S,S',S'',T,O; % soleil réel S = point 1.2 of el; % soleil déplacé S'= point 1.2 of cp; % terre T = (sqrt(a**2-b**2),0); % origine du cercle principal O = (0,0); fill el withcolor .9white; fill (el cutafter S)--T--cycle withcolor (.8,.8,1); % axes draw (-1.1a,0) -- (1.1a,0); draw (0,-1.1a) -- (0,1.1a); draw cp; draw el; draw S'--(xpart S',0) dashed evenly scaled 1; draw O--S'; draw T--S; draw O--S withpen pencircle scaled .5 withcolor .5white; path t[]; t1 = (fullcircle scaled 20) cutafter (O--S'); t2 = ((fullcircle scaled 20) shifted T) cutafter (T--S); drawarrow t1; drawarrow t2; dotlabel.lft(btex $S(t)$ etex, S); dotlabel.urt(btex $S'$ etex, S'); dotlabel.lrt(btex $T$ etex, T); dotlabel.ulft(btex $A$ etex, (-a,0)); dotlabel.llft(btex $B$ etex, (0,b)); dotlabel.urt(btex $P(t=t_0)$ etex, (a,0)); label.llft(btex $x$ etex, (1.1a,0)); label.llft(btex $y$ etex, (0,1.1a)); label.lft(btex $b$ etex, (0,a/2)); label.top(btex $a$ etex, (-a/2,0)); label.lft(btex $r$ etex,.5[T,S]); label.urt(btex $u$ etex,point .5 of t1); label.urt(btex $v$ etex,point .5 of t2); dotlabel.llft(btex $O$ etex, O); label(btex $\mathcal{S}_t$ etex, 1/3*((a,0)+T+S)); endfig; end