\documentclass[border=10pt]{standalone}
\usepackage{lmodern}
\usepackage{upgreek}
\usepackage[inline]{asymptote}
\begin{document}
\begin{asy}[width=\the\linewidth,inline=true]
import graph;
import roundedpath;
import math;
//texpreamble("\usepackage{upgreek}");
defaultpen(fontsize(10pt));
real sc=2;
unitsize(sc*1bp);
// 1. bounding ellipse
guide ell=(150,60)..(75,120)..(3.4,60)..(75,0)..cycle;
// 2. day
pen penA=rgb(0.773,0.831,0.882);
pen penB=rgb(0.09,0.09,0.09);
pair a=(70,60);
pair b=(100,60);
fill(box((0,0),(90,120)),penA);
axialshade(box((0,0),(100,120)),penA,a, extenda=false,penB,b, extendb=false);
// night
fill(box((100,0),(150,120)),black);
// sun
pair sunPos=(51,107);
real sunR=3;
pen sunClr=rgb(0.98,0.973,0.149);
pen BorderPen=rgb(0.145,0.361,0.435)+1bp;
// sun beam
guide sunBeam=(2.5,0)--(Cos(360/16),Sin(360/16))--(Cos(360/16),-Sin(360/16))--cycle;
