Planet radius vs. insolation flux in Earth units and logarithmic scale. Error bars mark the position of GJ 3090 b (green) and GJ 1214 b (blue). The size of the symbols is proportional to the planet mass. Grey dots are planets listed in the NASA Exoplanet Archive (https:///exoplanetarchive.ipac.caltech.edu/) with radius uncertainties smaller than 20%. A Gaussian kernel density estimate is shown in different background shades of grey. A subset of planets whose stars have a T_eff < 4000 K is shown as red dots, and its Gaussian kernel density estimate is shown in different background shades of red. The histogram of the entire sample (grey) and the subset (red) is shown right of the panel. The black line shows the scaling relation for the radius valley predicted by the photoevaporation model of Lopez & Rice (2018). The two main overdensities are the mini-Neptunes (above the line) and the super-Earths (below the line). The scarcity of planets in the upper left part of the diagram is the so-called photoevaporation desert, hot-Neptune desert, or hot-super-Earth desert (Lundkvist et al. 2016).