This plot shows the density-flux distribution for exoplanets less than 20 Earth masses. Size of the planets are to scale. The inside of the planets are color coded by composition. The color of their outside borders correspond to the parent star spectral type. Mercury, Venus, Earth, and Mars are included for comparison. Data is from the NASA Exoplanet Archive. This is large plot intended for viewing at high resolutions, click to enlarge. Credit: PHL @ UPR Arecibo.