WHPI: A New Initiative on Solar Minimum

The Whole Heliosphere and Planetary Interactions (WHPI) is an international initiative focused around the solar minimum period that aims to understand the interconnected Sun-heliospheric-planetary system. The simpler magnetic configuration and infrequency of solar eruptions makes solar minimum an ideal time to determine how the Sun's radiative output, magnetic field and outflowing solar wind plasma interact with the background heliosphere, the Earth and the other planets. WHPI follows two similar initiatives during the previous solar minima in 1996 and 2008-2009. The success of these efforts relies on a broad participation of scientists worldwide and across disciplines. In 2019-2020 WHPI coordinated 3 different observing campaigns, each a solar rotation long: The first was on Mar 12 - Apr 8, 2019 and targeted two large, recurrent coronal holes and the associated high-speed solar wind streams, the second one on Jun 29 - Jul 26 2019 was centered on the total solar eclipse, and the third one on Jan 15 - Feb 11 2020 corresponded to the 4th Parker Solar Probe (PSP) encounter when the Earth and many space observatories were near-radially aligned with PSP. We describe the WHPI effort as an example of interdisciplinary collaboration and report on the preliminary science results obtained during the WHPI campaigns.