Abstract: An illuminated inflatable balloon, with an envelope inflated with a gas, is connected to the ground by an elongate element. The envelope encloses an electrical bulb connected to an electrical power supply. Spring loaded filar elements are sensitive to the deformation of the envelope, as well as the internal pressure of the gas. The spring loaded filar elements cooperate with a control hairpin for actuating a switch interposed in the connection between the bulb and the electrical supply in order to make and break the connection on either side of a predetermined threshold.