Sheyna Gifford

Mar 16th 2022

The Buzz About Weather on Other Planets: WASP 127-b


Far inside the habitable zone, 520 light-years from Earth, a strange planet whips around its parent star. WASP 127-b makes a bee-line from one side to the other in four days. Yet this wanderer is no winged Mercury. It’s not small or rocky. It orbits off-kilter, in the opposite direction of its parent star’s rotation — like a table tilted to the plane of the solar system. As far as exoplanets go, this planet is not quite like anything scientists have found before.

The existence of undiscovered and alien planets hold potential for new discoveries in space and science, including a look into weather on other planets. WASP 127-b is a gas giant, like Jupiter or Saturn. Unlike the two biggest planets in our solar system, this exoplanet is an order of magnitude closer to its star than Mercury is to our sun. It’s bigger than Jupiter, while only having 16% of Jupiter’s mass. That means the planet is sort of … puffy. Hot, fast and, for a planet, fluffy.

WASP 127-b’s Salt Clouds

One of the cool things about finding a planet this big and fluffy and this close to its star? Not only can you look at it — you can also look through the upper layers of its atmosphere. Scientists from around the world worked together to combine data from the Hubble Space Telescope and the European Southern Observatory’s VLT (Very Large Telescope) in Chile to watch one of the least dense planets discovered to date move in front of its star over and over again.

No research team had (successfully) tried using one ground-based telescope and one space-based telescope to go cloud-watching on another planet. Their powers combined, the two telescopes were able to watch light from WASP 127 filter through the layers of vapor hovering around this huge planet. Researchers now believe one of those vapor layers could possibly be water, and the other looks more like sodium. This could mean there are salt clouds, or at least salt in the clouds. No one is quite sure — yet.

Weather on other planets is fascinating because, unlike Earth, scientists have to pull out all the stops to even begin to measure it. There’s no walking outside, holding out a palm or consulting the neighbor whose knee always knows when it’s going to rain. Finding and measuring the composition of clouds on an alien world took two of the world’s biggest telescopes.

Death of a Gas Giant

WASP-12b, like WASP 127-b, is big, hot, fast and close to its star. In fact, it’s so close to WASP-12 that WASP-12b — which is 46% larger than Jupiter — is being literally pulled apart. Or rather, its nearness to the star heats up the gas, which rises so high that it literally falls away from the planet toward WASP-12. Researchers calculated that with the mass loss, WASP-12 only had 10 million more years of existence.

A similar fate may await WASP 127-b, another hot Jupiter. Hot Jupiters in general are becoming a popular topic in the exoplanet universe, mostly because they shouldn’t be there. Young stars have high winds that blow gas away. Even when it gets cool and quiet enough for the gas to settle down and collect into these hot Jupiters’ cores, they are huge and solid. In order to exist up close and personal with a star, the material from the planet’s core needs to find its way to the clouds. Then, that material needs to wander close to the parent star after the star has grown out of its initial, young-star, high-wind phase. That’s a lot of steps to become a hot Jupiter that gets just close enough to show us its cloud cover — but not close enough to get that cover ripped off by the star that bore it.

It’s strange to think how the same kind of star — a yellow G-type main sequence — can give birth to Earth while another creates conditions terribly adverse to any kind of life. WASP 127-b’s salt-filled clouds face a 2,000-degree Fahrenheit surface, and it’s getting even hotter.

Now that scientists can look into the atmospheres of worlds far, far away using multiple telescopes, exoplanetary meteorology (or “alien cloud spotting”) could take researching weather on other planets to entirely new heights.

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