Radio waves passing through the solar corona, the outer atmosphere of the Sun, are distorted just like the air shimmers over scorching asphalt. This haze is caused by seething streams of charged particles — the solar wind. Scientists found a way to use the strength of the signal shimmer to simultaneously determine wind speed and particle density (mostly protons, hydrogen nuclei, and electrons). Previously, such measurements required knowing the type of turbulence, but the new method bypasses that: it directly captures how the spectrum of the radio waves blurs.

An unexpected twist: key data came from the Japanese Akatsuki spacecraft, which studies Venus. Its radio signals, passing near the Sun, became an ideal probe for the corona. The method works great for fast and uniform wind, but for slow wind that bursts out in clumpy streams, a correction for inhomogeneities was needed.