Some giant planets may haveĚýtwo enormous pairs of storms that stir up their atmospheres. These colossal couples, called modons, spin in opposite directions and are expected to completely dominate the dynamics of their worlds.
Many huge exoplanets that orbit close to their stars, called hot Jupiters, are expected to become tidally locked, meaning that the same side of the planet faces the star at all times. BecauseĚýthe heat from the star is always deposited in the same spotĚýon the planet, this can cause strange weather phenomena.
Jack Skinner at Queen Mary University of London and James Cho at the Flatiron Institute in New York used a series of high-resolution simulations to investigate these effects. They found that this one-sided heating creates jets and walls of gas that become two pairs of tornado-like storms – one pair near the equator, and another near the poles.
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“This should generate the largest storms ever to be found on planets – they’re huge,” says Cho. “These modons are roughly 7 or 8 times bigger than Jupiter’s Great Red Spot, which is the biggest storm we know of thus far.” In the simulations, these modons rapidly stirred up the atmosphere, generating thousands of smaller storms and spreading the heat around the planet.
“It’s quite different to what people typically thought these planets looked like from prior simulations,” says Skinner. “We thought that they were quite sluggish, not very dynamic, but what we’re seeing are these really violent storms whipping around the planets.” The modonsĚýcan make a complete circuit around a planet in a matter of days, traveling around 500 metres per second, he says.
This is likely to occur on all sorts of planets that are tidally locked with their stars, even rocky worlds, but it probably would not affect a planet’s habitability, Skinner says. “The planet would have to be very close to its star for modons to occur, so it’s very unlikely that it would be habitable anyway,” he says. However, examining how modons affect their host planets may be crucial to understanding the hottest worlds in the universe.
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