Till now, the place where music and astronomy were meeting was in outer space, more specifically in plasma waves. Those are produced in the space that surrounds the earth, generating a perceptible sound from the earth through radio waves.
A whistle. An onomatopoeia. A "fiiiiiiu".
FIU* is an electronic music and astronomy festival at the Yebes Astronomical Center (Guadalajara, Spain) that uses onomatopoeias as a graphic system.