When you look at the stars at night, you'll notice that they `twinkle'. This is not because the star is changing, but because the Earth's air is constantly shifting around.

Above the Earth's atmosphere, the solar wind blows past us, and this can also make stars twinkle. In fact, if we look at the radio waves coming from stars, the solar wind causes a stronger amount of twinkling in them than the Earth's atmosphere does in visible light.

So, what I do is look at a particular type of star called a radio star and measure how much it twinkles.

Periodic storms happen when there's a change from slow to fast wind. Between the two is an area where the gases in the wind are squashed which we call a compression region.

As this region travels away from the Sun, it can go in front of some of my radio stars and I can see the stars twinkle. This can allow me to see how fast the region is travelling.