New Horizons reveals Pluto's surprising blue twilight from organic haze

In the hours after New Horizons swept past Pluto on July 14, 2015, the spacecraft turned back toward the dwarf planet and found something no one had predicted: a thin, luminous blue halo encircling a world whose surface is grey and red. The colour belongs not to Pluto itself but to the physics of tiny organic particles suspended in its near-vacuum atmosphere, scattering short wavelengths of sunlight along long slant paths in a geometry that only a departing spacecraft could reveal. It is a reminder that the most profound discoveries often come not at the moment of arrival, but in the act of lo