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Category 5! Astronomers have for the first time measured wind speeds on an exoplanet and they are a doozy!
Discovered on the exoplanet HD 189733b, the Warwick researchers measured the velocities on the two sides of HD 189733b and found a strong wind moving at over 5400 mph blowing from its dayside to its night side. Mr Louden explains: “HD 189733b’s velocity was measured using high resolution spectroscopy of the sodium absorption featured in its atmosphere. As parts of HD 189733b’s atmosphere move towards or away from the Earth the Doppler effect changes the wavelength of this feature, which allows the velocity to be measured.”.
This exoplanet was one of the first discovered by Kepler, which means its orbit transits its sun. In this case it does so every 2.2 days, and astronomers have taken advantage of these frequent transits to study the planet’s atmosphere as the star’s light travels through it. The result is that HD 187733b is probably one of the most studied exoplanets.