NASA’s New Horizons spacecraft has transmitted images back to Earth that provide evidence of a colourful blue sky reaching high above the distant dwarf-planet of Pluto.
Much like Earth, the skies of Pluto would appear vibrantly blue when viewed from the surface, according to the findings of the New Horizon’s main imaging system. This latest finding is just one of many being drawn from a flood of data being streamed to NASA scientists by the New Horizons probe after it made a close fly-by of Pluto in June 2015.
Gas particles in the atmosphere of a planet scatter light waves to produce a colour. Discovering that Pluto’s atmosphere scatters light into a blue tint has caused great intrigue among planetary scientists.
“That striking blue tint tells us about the size and composition of the haze particles,” said science team researcher Carly Howett, from the Southwest Research Institute, Colorado. “A blue sky often results from scattering of sunlight by very small particles. On Earth, those particles are very tiny nitrogen molecules. On Pluto they appear to be larger – but still relatively small – soot-like particles we call tholins.”
Tholin particles form high in the atmosphere where sunlight breaks them apart into positively and negatively charged ions. They fall through the atmosphere, recombining on the way down to become complex macromolecules. The freezing temperatures on Pluto would cause these particles to condense and become like a frost that settles on the surface of the dwarf planet. The data was gathered by the New Horizons Ralph/Multispectral Visible Imaging Camera (MVIC).
Very little was known about Pluto until the New Horizons mission drew closer to the dwarf planet. Pluto is over 3.5 billion miles away from Earth and because of its distant orbit from strong sunlight, it is very hard to observe with even the most powerful scientific telescopes.
New Horizons was launched by NASA in 2006 from Cape Canaveral. It spent nearly a decade hurtling through our solar system before passing Pluto. New Horizons committed its resources to gathering as much information as possible while on its flyby. With its closest approach only lasting a few hours, New Horizons gathered data on Pluto’s geology, morphology, surface chemical compositions, atmospheric data and high resolution images of the planet’s moons. At a distance of 4.5 light hours away from Earth, the craft can only transmit data at one to three kilobytes per second.
The probe’s mission is ongoing, with its present course taking it into the collection of asteroids on the edge of our solar system known as the Kuiper belt. There it will be tasked with taking more up close readings of Kuiper belt objects similar to Pluto, continuing to fulfil purpose of exploring the unknown.