This coin celebrates the launch of the first earth satellite. The satellite emitted a radio signal on two frequencies and studied the upper layers of the ionosphere. Worldwide, radio enthusiasts tracked the sound signals transmitted by the satellite. It was visible as a first-magnitude star even to the naked eye. The satellite launch is said to have marked the start of the space age. Ukrainian scientists and designers contributed to the satellite`s development and launch, which was headed by the spaceflight pioneer Sergei Korolev.