\documentclass{standalone}
%
\usepackage{tikz}
\usetikzlibrary{backgrounds,decorations.pathmorphing,arrows.meta}
\usepackage{tkz-euclide}
%
\usepackage{xcolor}
%
\definecolor{core1}{HTML}{FF5E16}
\definecolor{core2}{HTML}{FF9616}
\definecolor{core3}{HTML}{FFD016}
%
\usepackage{fontspec}
\setmainfont{Open Dyslexic}
%
\title{Struttura del Sole}
\begin{document}
	\tikzset{
		partial ellipse/.style args = {#1:#2:#3}{insert path={+ (#1:#3) arc (#1:#2:#3)}},
	}
	\begin{tikzpicture}[background rectangle/.style={fill=white},show background rectangle,>={[inset=0,angle'=27]Stealth}]
		%
		\begin{scope}
			\draw [fill=core1,ultra thick] (15,0) circle (10cm);
			\draw [fill=core3] (15,0) [partial ellipse=-90:90:9.5 and 9.5] (15,0) [partial ellipse=90:270:7 and 9.5];
			\draw [fill=core2] (15,0) [partial ellipse=-90:90:9 and 9] (15,0) [partial ellipse=90:270:4 and 9];
			\draw [fill=core3] (15,0) [partial ellipse=-90:90:5 and 5] (15,0) [partial ellipse=90:270:2 and 5];
			\draw (15,9.5) -- (15,-9.5);
			\draw [fill=white] (15,0) [partial ellipse=-90:90:2 and 2] (15,0) [partial ellipse=90:270:0.7 and 2];
		\end{scope}
	\end{tikzpicture}
\end{document}