The Sphere #6, by Arnaldo Pomodoro, a 47.5" diameter bronze sculpture, is located (at least in 1984) at the Hirshhorn Museum and Sculpture Garden, on the Mall, in Washington DC.
It figures on the cover of NASA's Science Working Group report on the Study of Solar Oscillations from Space (Noyes & Rhodes, July 1984) that lead to the SOI/MDI instrument.
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Sylvain G. Korzennik (skorzennik@cfa.harvard.edu)