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48 JULY-AUGUST 2022 ASTRO PUBLISHING Here’s why Uranus and Neptune are different colors N ASA’s Voyager 2 spacecraft cap- tured these views of Uranus (on the left) and Neptune (on the right) during its flybys of the planets in the 1980s. [NASA/JPL-Caltech/B. Jónsson] N eptune and Uranus have much in common — they have similar masses, sizes, and atmospheric compositions — yet their appearances are notably different. At visible wavelengths Neptune has a distinctly bluer color whereas Uranus is a pale shade of cyan. Astronomers now have an explanation for why the two planets are dif- ferent colors. New research suggests that a layer of concentrated haze that exists on both planets is thicker on Uranus than a similar layer on Neptune and ‘whitens’ Uranus’s ap- pearance more than Nep- tune’s. If there were no haze in the atmospheres of Nep- tune and Uranus, both would appear almost equally blue. This conclusion comes from a model that an international team led by Patrick Irwin, Professor of by NOIRLab Amanda Kocz