Solar Wind Model Supported by Parker Solar Probe Observations During Faint Venusian Auroral Emission

The encounter of the Parker Solar Probe (PSP) with Venus during the Venus Gravity Assist 3 on 2020 July 11 provided a unique opportunity to gather in situ solar wind data in the Venusian environment while also being able to observe Venus from ground-based facilities on Earth. The Wang-Sheeley-Arge (WSA) model was used to make accurate predictions of solar wind velocity and interplanetary magnetic field polarity at Earth and STEREO-A, as compared to in situ data at each spacecraft. The same model was then used to predict solar wind conditions at Venus. The predictions were in good agreement with in situ PSP data, as they match the overall magnitude and structure of the solar wind velocity and magnetic polarity at multiple spacecraft. This demonstrates that WSA can be used to make reliable predictions at locations in the heliosphere when in situ data is not available. Venusian aurorae were detected via emission in the oxygen green line 5577 Å OI(¹ S - ¹ D) at the same time that PSP captured a heliospheric current sheet crossing, and shortly thereafter, detected an increase in proton count rate. This is the first observation of oxygen green line aurora on Venus that is not the direct result of a coronal mass ejection, a solar flare, or corotating interaction regions.