Tracks left behind by the November 2000 Leonids shower, as detected by ESA scientists. Each time a meteor crosses the atmosphere, it leaves behind a short trail of ionised particles. This trail reflects high-frequency radio signals from stations around the world for just a few seconds. The motion of the meteor trail due to the upper atmosphere winds changes the frequency of the reflected signal (Doppler effect). You 'hear' the trail as it is blown around by the winds before it is eventually dispersed. Part of the Space is the Place project - for more information, see http://www.citiesandmemory.com/space Recording by the European Space Agency.
