Tikz 3D - Onion layers

Question

Am not acquainted yet with 3D diagrams in TikZ and I would like to draw something like the picture attached. Does anybody have any helpful hints?

Answer 1

OK, I'll give it a try in 2D, just to let you start.

\documentclass[border=10pt]{standalone}
\usepackage{tikz}
\begin{document}
    \pagecolor{black}
\definecolor{col1}{RGB}{255,255,153}
\definecolor{col2}{RGB}{153,51,0}
\definecolor{col3}{RGB}{209,209,224}
\definecolor{col4}{RGB}{0,230,115}
\definecolor{col5}{RGB}{204,0,204}
\definecolor{col6}{RGB}{255,204,204}
\definecolor{col7}{RGB}{0,153,254}
\definecolor{col8}{RGB}{255,80,80}

\begin{tikzpicture}
    \coordinate (C) at (0,0);

    \fill[outer color=black,inner color=col1] (C) circle (7 cm);
    \fill[ball color=col1,shading=ball] (C) circle (5 cm);
    \begin{scope}
        \clip (0,-5) rectangle (5,5);
        \foreach \r [count=\i from 1] in {5,4.8,4.6,3,2.5,2.2,1.8,1.6}
            {
            \fill[outer color=col\i,inner color=col\i!70!black] (C) circle (\r cm);
            }
    \end{scope}

    \begin{scope}
        \clip (0,-5) rectangle (-5,5);
        \foreach \r [count=\i from 1] in {5,4.8,4.6,3,2.5,2.2,1.8,1.6}
            {
            \filldraw[col\i!70!black] (C) ellipse (0.3*\r cm and \r cm);
            }
    \end{scope}

    \begin{scope}
        \clip (90:1.6) arc (90:270:0.3*1.6 cm and 1.6 cm) arc (-90:90:1.6);
        \filldraw[ball color=col8,shading=ball] (C) circle (1.6 cm);
    \end{scope}
\end{tikzpicture}

\end{document}

EDIT: I edited my script to eliminate redundancies and inappropriate class declaration, and above all, to let you define once and for all the slices radii. I tried to add some shading into each slice but it's not working yet (apart from writing each slice in an individual code line, which I find disappointing). I'll let you know later if I find a way to do that correctly.

\documentclass[tikz,border=10pt]{standalone}
\begin{document}
    \pagecolor{black}
\definecolor{col1}{RGB}{255,255,153}
\definecolor{col2}{RGB}{153,51,0}
\definecolor{col3}{RGB}{209,209,224}
\definecolor{col4}{RGB}{0,230,115}
\definecolor{col5}{RGB}{204,0,204}
\definecolor{col6}{RGB}{255,204,204}
\definecolor{col7}{RGB}{0,153,254}
\definecolor{col8}{RGB}{255,102,0}

\begin{tikzpicture}
    \coordinate (C) at (0,0);

    \def\a{5}   \def\b{4.8}  \def\c{4.6} \def\d{3}
    \def\e{2.2} \def\f{1.8}  \def\g{1}   \def\h{0.8}

    \fill[outer color=black,inner color=col1] (C) circle (6.5 cm);
    \fill[ball color=col1,shading=ball] (C) circle (5 cm);

    \begin{scope}
        \clip (0,-5) rectangle (5,5);
        \foreach \r [count=\i] in {\a,\b,\c,\d,\e,\f,\g,\h}
            {
            \fill[outer color=col\i,inner color=col\i!70!black] (C) circle (\r cm);
            }
    \end{scope}

    \begin{scope}
        \clip (0,-5) rectangle (-5,5);
        \foreach \r [count=\i] in {\a,\b,\c,\d,\e,\f,\g,\h}
            {
            \fill[col\i!70!black] (C) ellipse (0.3*\r cm and \r cm);
            }
    \end{scope}

    \begin{scope}
        \clip (90:\h) arc (90:270:0.3*\h cm and \h cm) arc (-90:90:\h);
        \fill[ball color=col8,shading=ball] (C) circle (\h cm);
    \end{scope}

\end{tikzpicture}

\end{document}