The theremin is one of the earliest examples of a musical instrument, invented in the 1920s by Leon Theremin. It's controlled using a couple of antennae, which detect the position of the musician's hand using electrical signals, and are then amplified through to a speaker. As it happens, the signals produced by the theremin can easily travel interstellar distances, which in 2001 led Russian scientist Alexander Zaitsev to propose that humanity composes a Theramin-based concert, which we could then broadcast out to neighbouring stars. Zaitsev's initial requests were rejected on the grounds that broadcasting humanity's presence could put it at the mercy of more advanced extra-terrestrial civilisations. Eventually he got his way however, and a trio of musicians composed seven Russian folk songs on the theremin. The songs were sent to the nearest stars via the Yevpatoria RT-70 telescope in 2001, and are expected to reach six neighbouring stars between the years 2047 and 2070.