The European Space Agency's (ESA) Cluster mission is snooping in on the sounds of Earth - and is getting an ear-full.

In fact, the first thing a distant extraterrestrial civilization might pick up from our blue planet is the buzz of chirps and whistles. The ESA Cluster mission is showing scientists how to understand the sounds of Earth, valuable clues as to what we should be listening for in future searches for alien worlds.

The data used in the ESA study was collected by the NASA Wide Band instrument flying onboard the four Cluster spacecraft.

To give a listen to your own planet - as heard by the Cluster spacecraft - check out:

http://www.esa.int/esaCP/SEMLX5SHKHF_index_0.html

-- Leonard David