pgfplots：如何在球面添加直线

Question

我有一个球体：

我想说明一下：光在1秒内传播的距离相当于绕地球7.5圈的距离。

那么，我该如何添加（7.5）绕线像这样：

\documentclass[margin=5mm, tikz]{standalone}
\usepackage{pgfplots}
\pgfplotsset{compat=newest}
\begin{document}
\begin{tikzpicture}
\begin{axis}[%
axis equal,
width=10cm,
height=10cm,
axis lines = center,
xlabel = {$x$},
ylabel = {$y$},
zlabel = {$z$},
ticks=none,
enlargelimits=0.3,
view/h=45,
scale uniformly strategy=units only,
]
\addplot3[%
surf,
%opacity = 0.2,
colormap={bw}{color=(lightgray) color=(lightgray)},% lines 1/2
ultra thin,% lines 2/2
color=gray!22,  % surface
z buffer = sort,
samples =33,
variable = \u,   variable y = \v,
domain = 0:180,    y domain = 0:360,
]
({cos(u)*sin(v)}, {sin(u)*sin(v)}, {cos(v)});
end{axis}
\end{tikzpicture}
\end{document}