Helium filled balloons with built-in, ultra-bright LEDs form a cloud which floats around in the sky at 100m. This balloon-formation reacts to the changing electromagnetic fields that are created by distant storms, police and traffic radio-waves or television transmittals, and which change the colour and colour-intensity of the balloons. Through countless variations of colour, 'Sky Ear' demonstrates the invisible topography which permanently surrounds us. The glowing cloud not only shows the extent to which natural electromagnetism penetrates our environment, but demands that the audience interact with the fields. Mobile telephones are embedded in the balloons. By telephoning into the ‘Sky Ear' the audience is able to see how the local magnetic field is changed by telephone activity; our daily interaction with electromagnetic fields is rendered visible.