Antonio Manaytay – Fourth Estate Contributor
Santa Barbara, CA, United States (4E) – The tiny planet Pluto at the fringes of the solar system has a novel cooling mechanism that keeps its temperature way cooler than expected. This cooling mechanism, according to a study, is largely controlled by infrared radiation emitting haze particles into space.
The study, published on November 16 in Nature, said this unique cooling mechanism of the dwarf planet had kept its atmospheric temperature frigid – about 70 Kelvin (-203 degrees Celsius or -333 degrees Fahrenheit). This was way lower than previously predicted at about 100 Kelvin (-173 degrees Celsius or -280 degrees Fahrenheit).
The previous prediction of Pluto’s temperature was based on the gas composition of its atmosphere, which generally determines the amount of heat being trapped. NASA’s New Horizons spacecraft in 2015, however, had taken a much cooler temperature as it passed by the dwarf planet in its journey outside the solar system.
“It’s been a mystery since we first got the temperature data from New Horizons,” study’s first author Xi Zhang, an assistant professor of Earth and planetary sciences at the University of California Santa Cruz, said.
“Pluto is the first planetary body we know of where the atmospheric energy budget is dominated by solid-phase haze particles instead of by gases,” Zhang said.
The team’s hypothesis of this cooling mechanism, according to Zhang, could be confirmed by the James Webb Space Telescope, set to be launched in 2019. The powerful telescope could detect the excess radiation emitted by the haze particles into space.
The images taken by the New Horizons revealed extensive layers of haze in the planet’s atmosphere due to chemical reactions that occur in the upper atmosphere. It is in the upper atmosphere where the radiation emitted by the sun ionized the nitrogen and methane forming nanometer-sized hydrocarbon particles.
These hydrocarbon particles, the study proposes, descend through the layers of the atmosphere forming aggregates together. The aggregates grow larger and finally settle on the planet’s surface.
These tiny particles, Zhang said, are “related to the reddish and brownish stuff seen in images of Pluto’s surface.”
Zhang and his colleagues are looking at what the haze particles could do on the balance of atmospheric energy of other planetary bodies.
The findings of the research, which was funded by NASA, may help explain why some exoplanets have hazy atmospheres.
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