The latest New Horizons photos have arrived, and these ones reveal that the sky on Pluto is blue too.
Scientists continue to be amazed by the seemingly endless stream of photos from the New Horizons space probe, and the latest shots of the distant dwarf planet are no exception. According to a report from Astronomy.com, the most recent pictures of Pluto from New Horizons reveal a stunning blue sky and frozen water on the planet’s surface.
Principal investigator Alan Stern from the New Horizons Southwest Research Institute in Boulder, Colorado was stunned by the discovery, calling the blue sky on Pluto “gorgeous.”
The blue sky on Pluto is not that different from the blue sky on Earth. The particles floating in Pluto’s atmosphere are likely grey or red, but they scatter light bouncing off them at a wavelength that falls in the blue range of the spectrum. According to New Horizons team researcher Carly Howett, “That striking blue tint tells us about the size and composition of the haze particles. A blue sky often results from scattering of sunlight by very small particles.”
The particles that scatter blue light on Earth are primarily made of nitrogen molecules. On Pluto, the light is scattered by slightly larger particles that hang in the air like soot, called tholins.
Ultraviolet light penetrates Pluto’s atmosphere and splits and ionizes nitrogen and methane molecules from the tholins. These form more complex charged ions that recombine into even more complex macromolecules that collectively form the tiny soot particles in the sky.
The photos also revealed the presence of water ice on Pluto. It is unclear if the two discoveries are related on a deeper level at this point.