Phase reddening on various Solar System airless bodies. The degree of phase reddening is measured by the variations in spectral slope with increasing phase angle. The Moon by Lane & Irvine (1973), Ceres by Ciarniello et al. (2017), Vesta by Schröder et al. (2014a), Eros by Clark et al. (2002), Itokawa by Tatsumi et al. (2018), 67P/Churyumov-Gerasimenko by Fornasier et al. (2015), and Bennu by DellaGiustina et al. (2019) are plotted with Ryugu (square). The effect on Eros was measured in the near-infrared, 1.5–2.3 μm, and other objects are measured in the visible wavelength range.