Discover exoplanets with yellow skies and iron rain

NASA astronomers found a planet with an unusual atmosphere, called WASP-79b, about 800 light-years from Earth.

As described in the Astronomical Journal , WASP-79b has yellow skies instead of blue like our planet. It orbits its host star CD-30 1812 in the constellation Ba Giang (Eridanus) and completes an orbit every 3.7 days. 

The graphic depicts the planet WASP-79b orbiting the star many times larger than the Sun. (Photo: NASA).

The planet is not in a habitable zone, meaning no liquid water exists on the surface. With an average temperature of up to 1650 ℃, it is one of the hottest exoplanets ever discovered. 

"WASP-79b is twice as heavy as Jupiter and is so hot that it has an expanding atmosphere - the ideal condition for studying starlight. The planet also has scattered iron clouds raised to a possible height. precipitates and falls like rain, " explains NASA.

Lead researcher Kristin Showalter Sotzen from the US Johns Hopkins University emphasized that the WASP-79b has an atmospheric process unlike any physical model. Scientists do not observe the sign of "Rayleigh scattering" - the phenomenon of very small particles of dust high upward that causes different wavelengths of light to scatter. Rayleigh scattering explains why Earth has a blue sky.

"Because this is the first time seeing this, we have not been able to understand the cause," Sotzen said. "We need to keep an eye out for similar exoplanets in the future because they could be a sign of an unknown atmospheric process."

For the study, Sotzen and colleagues used NASA's Hubble space telescope and ESA, in conjunction with the Magellan II ground telescope system at the Las Campanas Observatory in Chile. At the next stage, astronomers hope to use the James Webb space telescope - expected to be launched in 2021 - to make better observations, helping to analyze the chemical composition of WASP-79b atmosphere.

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