%Draw a Shrere of the Earth
x = zeros(37,37);
y = zeros(37,37);
z = zeros(37,37);
r=6378100;%Equitorial Radius of the Earth
for phi = 1:11
    for th = 1:37
        x(th,phi) = r * cos(10 * (th-1)) * sin(36 * (phi-1));
        y(th,phi) = r * sin(10 * (th-1)) * sin(36 * (phi-1));
        z(th,phi) = r * cos(36 * (phi-1));
        plot3(x(1:th,phi),y(1:th,phi),z(1:th,phi),'-y')
        hold on;
    end;
end;
hold on;
%Tilt Maxima and Minima
rt=6378100;
phit(1) = (90-23.439281/2)*pi/180;
phit(2) = (90+23.439281/2)*pi/180;
xt = zeros(37,37);
yt = zeros(37,37);
zt = zeros(37,37);
for h=1:2
    for tht = 1:361
    xt(tht) = r * cos(1 * (tht-1)) * sin(phit(h));
    yt(tht) = r * sin(1 * (tht-1)) * sin(phit(h));
    zt(tht) = r * cos(phit(h));
    plot3(xt(1:tht),yt(1:tht),zt(1:tht),'-r')
    hold on;
    end;
end;
%Center ring
phic = 90*pi/180;
tilt = 23.439281*pi/180;
xc = zeros(37,37);
yc = zeros(37,37);
zc = zeros(37,37);
for thc = 1:361
    xc(thc) = (r * cos(1 * (thc-1)) * sin(phic));
    yc(thc) = (r * sin(1 * (thc-1)) * sin(phic));
    zc(thc) = (r * cos(phic));
    plot3(xc(1:thc),yc(1:thc),zc(1:thc),'-g')
    hold on;
 end;