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Astronomers Measure 8700 km/h Winds On Alien Planet HD 189733b

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Astronomers Measure 8700 km/h Winds On Alien Planet HD 189733b

For the first time, a team of scientists have managed to record winds speed on opposite sides of an ‘alien’ planet, dubbed HD 189733b, this extreme planet is being battered by furious winds of more than 8700 km/h (5400mph) — 20 times higher than the fastest wind speed ever recorded on Earth — equivalent to seven times sound’ speed.

This discovery was made by astronomers at the University of Warwick in England, with help from the High Accuracy Radial velocity Planet Searcher (HARPS), an advanced planet-hunting spectrograph. It is the first time that a weather system on a planet outside of our own solar system has been directly mapped and measured for speed.

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,

said Tom Louden ~ lead researcher of the study.

Planet HD 189733b is one of the most studied class of planets known as ‘hot Jupiters’. Discovered in 2005, this gas giant planet is only 1.2 times bigger than Jupiter but is 180 times closer to its star, HD 189733, orbiting it once every 2.2 days. With a temperature of 1800©C, HD 189733b is decidedly inhospitable and unlikely to support life. It is located toward the constellation Vulpecula, also known as the ‘little fox’, some 63 light-years away from us ~ 600 trillion km (370 trillion miles).

To make their findings, the researchers measured the velocities on two sides of the planet. They spotted a torrential wind with speeds of over 5,400 miles per hour moving from the daytime side to the nighttime side. They were able to measure these velocities using high-resolution spectroscopy of the Sodium absorption present in the planet’s 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,

Louden explained.

The surface of the star is brighter at the center than it is at the edge, so as the planet moves in front of the star the relative amount of light blocked by different parts of the atmosphere changes. For the first time, we’ve used this information to measure the velocities on opposite sides of the planet independently, which gives us our velocity map.

Scientists say their discovery will help astronomers study the atmospheres of small, rocky planets outside our solar system.

We are tremendously excited to have found a way to map weather systems on distant planets,

study co-author Peter Wheatley said.

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.



  • Feature image: ©Mark A. Garlick / University of Warwick.

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