Is the pale blue dot unique?

Voyager 1’s iconic image of the Pale Blue Dot shows hints of Earth’s uniqueness are visible from great distances; the pale blue color of Earth sets it apart from other objects in our Solar System. But could planet color be used to easily identify Earth-like exoplanets? UWAB graduate students Joshua Krissansen-Totton, Edward Schwieterman, Giada Arney, former VPL grad student Tyler Robinson, postdoc Benjamin Charnay, Professosr Victoria Meadows, and David Catling have authored a paper on whether color can be used to distinguish Earth-like exoplanets from uninhabitable worlds. This paper shows that numerous uninhabitable planets – particularly icy worlds with thick atmospheres – could mimic the Earth’s pale blue color. It is possible to distinguish these icy worlds from Earth-like planets with extremely precise color observations, but this level precision demands a lot of telescope time. This suggests that spectral observations may be preferable to color observations for identifying Earth-like exoplanets.