Astronomers have discovered a cloud-free exoplanet for only the second time ever. It’s the first Jupiter-like planet that doesn’t have clouds or haze in the observable atmosphere. The plan is called WASP-62b; a gas giant first detected in 2012 using the Wide Angle Search for Planets (WASP) survey. The recent study marks the first time its atmosphere has been scrutinized.
The planet is known as a hot Jupiter and is 575 light-years away. It’s about half the mass of Jupiter but orbits its host star much quicker than Jupiter does. WASP-62b completes an orbit around its host star in only 4.5 days. The close proximity to the host star makes it extremely hot. Data on the planet’s atmosphere was recorded using spectroscopy as it moved in front of the host star on three separate occasions.
Researchers made visible light observations which can detect the presence of sodium and potassium in the atmosphere. There was no evidence of potassium in the atmosphere, but there was clear evidence of sodium. Since clouds or haze would obscure the full signature of sodium, researchers concluded the planet has no clouds or haze in its atmosphere.
Typically the presence of sodium is typically only detected in small amounts due to most exoplanets having clouds or haze blocking its full signature. Planets with no clouds are extremely rare, with astronomers estimating less than seven percent of exoplanets have clear atmospheres. In addition to WASP-62b, the only other known exoplanet with a clear atmosphere is WASP-96b, classified as a hot Saturn.
Astronomers are keen to study exoplanets with no clouds in the atmosphere because they believe it will lead to a better understanding of how the planets formed. Astronomers and researchers are looking forward to the James Webb Space Telescope launch later this year as it will bring new opportunities to study and better understand WASP-62b.