Overview
- Researchers using BiSON’s more than 40-year helioseismic record compared four solar minima spanning 1985 to 2019, as reported in Monthly Notices of the Royal Astronomical Society.
- The unusually long and quiet 2008–2009 minimum showed the strongest helium glitch and faster sound speeds in the Sun’s outer layers, indicating slightly higher pressure and temperature with weaker magnetic fields.
- The analysis shows successive minima are not identical in the Sun’s interior, with the 2008–2009 signature corresponding to the weak solar cycle 24 that followed.
- The team says solar-cycle and space-weather forecasting models must reproduce these measured structural shifts to capture key physics.
- Scientists emphasize maintaining continuous helioseismic monitoring and propose applying these methods to Sun-like stars with upcoming missions such as ESA’s PLATO.