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Forecasting the weather
on exoplanets

Posted: 29 March 2012

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It is difficult enough to predict the weather on planet Earth, but a team of scientists from Exeter University are working on models that predict and interpret weather and climate on extrasolar worlds.

David Acreman of Exeter University presented the team’s work at the National Astronomy Meeting today, explaining that sophisticated models developed by the Met Office for weather forecasting and climate studies on Earth could help interpret the wealth of data returned on extrasolar planets, and in turn provide new insight to climate on Earth.

“Many of the planets we find are hot jupiters, gas giants which orbit very close to their host stars,” he says. “They’re phase locked, so there’s one side in permanent daytime and one time in permanent nighttime. Consequently there’s a very large temperature difference, and this causes high speed winds to occur – up to a few kilometres per second.”

Watch David Acreman tell Astronomy Now about weather forecasting on exoplanets using Met Office models.

Such strong winds are capable of redistributing heat around the planet, affecting what astronomers see when they observe the planet. But there’s also another puzzle, Acreman tells Astronomy Now. “When we look at the size of these planets, which we can determine from observation, they are larger than models predict. It’s likely due to the distribution of heat within the planet, which causes the atmosphere to become inflated, but we hope that using that climate and weather model the Met Office has produced we can gain much better understanding of how these inflated hot jupiter planets arise.”

Clouds, haze and dust are another consideration for the model. Cloudy days on Earth are a familiar sight, but an exoplanet’s clouds contain exotic substances like titanium oxide. “Although this seems quite different from clouds on Earth we can translate a lot of the physics used in the Earth modelling to our exoplanets. And hopefully we can bring some of our understanding from exoplanets back to understanding clouds on Earth.”

The new model will eventually help identify molecules in the atmosphere that indicate life on exoplanets, such as oxygen, methane and water.

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