Shrinking sphere in LaTeX with PGF/TikZ

Example1.tex

\documentclass[crop=true, border=10pt]{standalone}

 
\usepackage{graphicx}
\usepackage{xcolor}

\usepackage{tikz}
\usetikzlibrary{arrows.meta}

\usepackage{tikz-3dplot}

\usepackage{pgfplots}
\usepgfplotslibrary{fillbetween}

\definecolor{plum}{rgb}{0.36078, 0.20784, 0.4}
\definecolor{chameleon}{rgb}{0.30588, 0.60392, 0.023529}
\definecolor{cornflower}{rgb}{0.12549, 0.29020, 0.52941}
\definecolor{scarlet}{rgb}{0.8, 0, 0}
\definecolor{brick}{rgb}{0.64314, 0, 0}
\definecolor{sunrise}{rgb}{0.80784, 0.36078, 0}
\definecolor{lightblue}{rgb}{0.15,0.35,0.75}



\begin{document}

\begin{tikzpicture}[scale=.6]
	% Draw the grid.
	\draw [cornflower!20,step=0.25,thin] (-3,-3) grid (3,3);
	\draw [cornflower!40,step=1.0,thin] (-3,-3) grid (3,3);

	\node at (0,-3.6) [xshift=0em, yshift=0em] {$R_1$};
 
    \draw (-2,0) arc (180:360:2cm and 0.6cm);
    \draw[dashed] (-2,0) arc (180:0:2cm and 0.6cm);
    \draw (0,0) circle (2cm);
    \shade[ball color=lightblue!40!white,opacity=0.40] (0,0) circle (2cm);
\end{tikzpicture}	
%
\hskip.5em
%
\begin{tikzpicture}[scale=.6]
	\draw [cornflower!20,step=0.25,thin] (-3,-3) grid (3,3);
	\draw [cornflower!40,step=1.0,thin] (-3,-3) grid (3,3);

	\node at (0,-3.6) [xshift=0em, yshift=0em] {$R_2 = 0.6 \times R_1$};

 
    \draw (-.6*2,0) arc (180:360:.6*2cm and .6*0.6cm);
    \draw[dashed] (-.6*2,0) arc (180:0:.6*2cm and .6*0.6cm);
    \draw (0,0) circle (.6*2cm);
    \shade[ball color=lightblue!50!white,opacity=0.50] (0,0) circle (.6*2cm);
\end{tikzpicture}	
%
\hskip.5em
%
\begin{tikzpicture}[scale=.6]
	\draw [cornflower!20,step=0.25,thin] (-3,-3) grid (3,3);
	\draw [cornflower!40,step=1.0,thin] (-3,-3) grid (3,3);

	\node at (0,-3.6) [xshift=0em, yshift=0em] {$R_3 = 0.3 \times R_1$};

    \draw (-.3*2,0) arc (180:360:.3*2cm and .3*0.6cm);
    \draw[dashed] (-.3*2,0) arc (180:0:.3*2cm and .3*0.6cm);
    \draw (0,0) circle (.3*2cm);
    \shade[ball color=lightblue!60!white,opacity=0.60] (0,0) circle (.3*2cm);
\end{tikzpicture}	
%
\hskip.5em
%
\begin{tikzpicture}[scale=.6]
	\draw [cornflower!20,step=0.25,thin] (-3,-3) grid (3,3);
	\draw [cornflower!40,step=1.0,thin] (-3,-3) grid (3,3);

	\node at (0,-3.6) [xshift=0em, yshift=0em] {$R_4 = 0.1 \times R_1$};

    \draw (-.1*2,0) arc (180:360:.1*2cm and .1*0.6cm);
    \draw[dashed] (-.1*2,0) arc (180:0:.1*2cm and .1*0.6cm);
    \draw (0,0) circle (.1*2cm);
    \shade[ball color=lightblue!80!white,opacity=0.80] (0,0) circle (.1*2cm);
\end{tikzpicture}	



\end{document}