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what's twinkling got to do with it?

 

You’ve probably noticed that stars usually appear to "twinkle". This is not because the stars themselves are changing in brightness, but because the Earth's atmosphere is constantly moving. The atmosphere contains many moving patches of air that have different densities and temperatures. The light from the star coming through these patches is constantly refracted (bent) by different amounts and this makes the image appear to flicker. It’s a bit like watching the patterns of light on the bottom of a swimming pool

 
 

If you see a star that isn't twinkling, what's it likely to be? Well it could be an aircraft or a satellite, or maybe a planet

 
         

But it's not just the Earth's atmosphere that makes stars twinkle. The solar wind can have the same effect. When we look at radio waves coming from stars we see a lot of twinkling caused by refraction of the radio waves in the solar wind.

Space-weather storms happen when there's a change from a slow to a fast solar wind. Between the fast and slow solar winds there is a region where the wind is squashed, like cars in a traffic jam on a motorway. This is known as a compression region and it is the change in density across the compression region which causes the twinkling

When we detect a compression region, we know a solar storm is heading our way. By measuring how fast it's travelling, we can predict when it will arrive. And that's what I do... I look at distant stars that produce vast amounts of radio waves and see how much they twinkle due to the solar wind. This allows me to detect and measure any compression regions and so to provide space weather forecasts.

   

 

   
 
 

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