English: Section of the Earth–Moon system's trajectory around the Sun in proper scale.

  orbital path of the Earth
  orbital path of the Moon

Used parameters

import numpy as np import matplotlib.pyplot as plt rEM = 38 # SVG pixel per |Earth-Moon|; we're going to round to int. rSE = rEM*389.168 # pixel per |Sun-Earth| n = 10 # polygon segments per quarter month; with cubic splines, n = 1 would probably suffice. p = 12.4 # synodic months per year; 4*n*p segments per year. θ = 2*np.pi*np.arange(-n-1, 3*n)/(4*n*p) # one month xE = rSE*np.sin(θ) yE =-rSE*np.cos(θ) xM = rSE*np.sin(θ) + rEM*(np.sin(p*θ)*np.cos(θ) + np.cos(p*θ)*np.sin(θ)) # Rotate rM vector by Earth's arc angle. yM =-rSE*np.cos(θ) - rEM*(np.cos(p*θ)*np.cos(θ) - np.sin(p*θ)*np.sin(θ)) fig, ax = plt.subplots(figsize=(19,2.5)) ax.plot(xE, yE, 'b-', linewidth=.5) ax.plot(xM, yM, 'k-') ax.plot(xE[1::n], yE[1::n], 'bo', markersize=5) ax.plot(xM[1::n], yM[1::n], 'ko', markersize=2) fig.tight_layout() fig.show() xE = xE.astype(int) yE = yE.astype(int) xM = xM.astype(int) yM = yM.astype(int) rM = 8; rE = 20 # radii, not to scale (would be 0.17 and 0.63) open('out.svg', 'w').write(f<?xml version="1.0" encoding="UTF-8"?> <svg xmlns="http://www.w3.org/2000/svg" width="1600" height="{1600*(rSE+rEM+rM+yM[-1])/(xE[-1]-xE[0])}" viewBox="{xE[0]} {-(rSE+rEM+rM)} {xE[-1]-xE[0]} {rSE+rEM+rM+yM[-1]}"> <defs> <marker id="E" overflow="visible"><circle r="{rE}" fill="blue"/></marker> <marker id="M" overflow="visible"><circle r="{rM}" fill="black"/></marker> </defs> <path fill="none" stroke="blue" stroke-width="2" d="M{'L'.join([x+' '+y for x,y in zip(xE.astype(str), yE.astype(str))])}"/> <path fill="none" stroke="black" stroke-width="4" d="M{'L'.join([x+' '+y for x,y in zip(xM.astype(str), yM.astype(str))])}"/> <path fill="none" stroke="none" marker-start="url(#M)" marker-mid="url(#M)" marker-end="url(#M)" d="M{'L'.join([x+' '+y for x,y in zip(xM[1::n].astype(str), yM[1::n].astype(str))])}"/> <path fill="none" stroke="none" marker-start="url(#E)" marker-mid="url(#E)" marker-end="url(#E)" d="M{'L'.join([x+' '+y for x,y in zip(xE[1::n].astype(str), yE[1::n].astype(str))])}"/> </svg>

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