Why is the European Space Agency beaming a waltz at NASA's Voyager 1 probe this weekend?

A cylindrical spacecraft approaches a blue and white planet.

With its sweeping tempo and ethereal melody, Austrian composer Johann Strauss II's "The Blue Danube" waltz has become synonymous with outer space and science fiction ever since it was chosen by Stanley Kubrick for 1968's "2001: A Space Odyssey."

Now "The Blue Danube" waltz with its whirling orbital rhythms will truly become the music of the cosmos when the European Space Agency broadcasts the lilting classical piece into deep space in celebration of the agency's 50th anniversary this year, in addition to the bicentennial of Johann Strauss II's birth in 1825.