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Bruno Bavassano is a solar wind researcher whose publications connect spacecraft observations with the statistical behavior of magnetohydrodynamic turbulence. A 2003 study with Roberto Bruno, Vincenzo Carbone and Luca Sorriso-Valvo compared velocity and magnetic field fluctuations between $0.3$ and $1$ astronomical unit from the Sun. It separated fast from slow solar wind, and changes in field magnitude from changes in field direction.^[ref]

The diagnostic was scale-dependent kurtosis. For a fluctuation $X$ with mean zero, $K=\mathbb{E}[X^4]/\mathbb{E}[X^2{]}^2$ weights rare large events strongly. A Gaussian distribution has $K=3$; a rising value as the separation shrinks indicates that small-scale changes are becoming more unevenly distributed. The study found stronger intermittency in compressive magnetic fluctuations than in the corresponding velocity fluctuations, and a radial increase in fast-wind intermittency.^[ref]

For intuition, replacing one ordinary increment by an increment ten times larger multiplies its contribution to the fourth moment by $10^4$, rather than $10^2$ for its squared contribution. This is why a sparse set of sharp changes can matter even when most samples look modest.

Marco Malaspina is a science writer and interviewer whose signed work for Media INAF communicates research in astronomy and space physics. In a 2018 interview with Roberto Bruno, he discussed the physical questions behind measurements of the solar wind and turbulence, alongside the researcher's professional recognition.^[ref]

The article is a communication contribution, rather than a claim that Malaspina performed the spacecraft experiment. It gives readers access to the researcher's account of why irregular plasma fluctuations are scientifically interesting. Keeping that distinction explicit separates the writer who explains an observation from the investigators who measured and analyzed it. His bylined interview is also a useful identified source for Bruno's discussion of his research, with its original date preserved.

By Luca Sorriso-Valvo, Raffaele Marino, Vincenzo Carbone, Fabio Lepreti, Pierluigi Veltri, Alain Noullez, Roberto Bruno, Bruno Bavassano, Ermanno Pietropaolo.

Physical Review Letters 99, 115001 (2007), DOI doi.org/10.1103/PhysRevLett.99.115001 . Primary byline as listed in the archive. Abstract and mixed third-order structure functions: Ulysses velocity/magnetic observations and evidence of a magnetohydrodynamic inertial energy cascade.

Roberto Bruno is a physicist who studies the solar wind as a natural laboratory for turbulence. INAF's 2018 institutional interview documents his work on nonlinear processes in space plasmas and the American Geophysical Union's recognition of that work.^[ref]

His 2024 first-authored study examined proton and alpha particle populations measured by Solar Orbiter. Instead of characterizing all particles by one bulk value, the team used clustering to separate core and beam populations within the velocity distribution. That distinction changed the interpretation of temperature and its directional dependence, because two populations moving relative to one another can appear broader when combined.^[ref]

An illustrative calculation shows the issue. Two equally populated, individually narrow groups moving at $u-d$ and $u+d$ have combined mean $u$, but their relative drift contributes $d^2$ to the combined variance. Treating that whole width as random thermal motion would hide the organized relative motion. Measurements of a full velocity distribution can therefore reveal physics that one average speed cannot.