And I Thought Hurricanes on Earth Were Bad…

Our species is just now reaching the technology necessary to detect features of exoplanets, and not just the exoplanets themselves.  We have seen atmospheres, aurorae, and magnetism on distant worlds, and now we can add incredibly fast winds to that list.  A team of astronomers have discovered an exoplanet, classified as HD 189733b, that has wind speeds exceeding 8,500 km / h, or about 2 Km / s.

HD189733: The planet HD 189733b is shown here in front of its parent star. A belt of wind around the equator of the planet travels at 5400mph from the heated day side to the night side. The day side of the planet appears blue due to scattering of light from silicate haze in the atmosphere. The night side of the planet glows a deep red due to its high temperature. Credit: Mark A. Garlick/University of Warwick

Lead researcher Tom Louden, of the University of Warwick’s Astrophysics group, said: “This is the first ever weather map from outside of our solar system. Whilst we have previously known of Wind on exoplanets, we have never before been able to directly measure and map a weather system.”

The group looked at the doppler effect on absorption lines of Sodium in the planet’s spectrum.  Measuring how the wavelength of those lines was compressed or extended, ie blueshifted or redshifted, they could determine the speed of the atmospheric Sodium toward or away from Earth.  The calculation gave an incredible measurement of the wind speeds on this distant world.

The wind speeds are 20 times greater than the speediest winds on Earth, and would easily pick a person up off the ground, like a powerful tornado.  The planet HD 189733b is part of a class of planets known as ‘hot Jupiters,’ with a mass 10% greater than Jupiter, but a distance 180 times closer to its star.  This creates incredible temperatures on the star-facing side of the planet, but cooler conditions on the other side.  The movement of the expanding warm air on the hot side of the planet is causing the incredible winds as the atmosphere shifts to the cooler side.

The researchers say that the techniques used could help the study of Earth-like planets. Co-researcher, Dr Peter Wheatley of the University of Warwick’s Astrophysics Group explains: “We are tremendously excited to have found a way to map weather systems on distant planets. As we develop the technique further we will be able to study wind flows in increasing detail and make weather maps of smaller planets. Ultimately this technique will allow us to image the weather systems on Earth-like planets. ”

In our study of exoplanets, we push the limits of our technology.  Now that we have a technique to determine wind conditions on an exoplanet, we can use the same technique with future technology to look at the weather conditions on any exoplanet, not just the ones with extreme winds.  When we do find a twin of our own planet Earth, the techniques we have tested on other worlds will allow us to gain a solid scientific understanding of how it behaves.  This can give us the answer to the great question ‘can it support human life?’

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