2025-07-07 PUNCH Science Nugget
PUNCH is about to get a close look at a “point-of-no-return” zone surrounding the Sun. Charged particles fly away from the Sun in
the form of the steady solar wind and bursty coronal mass ejections (CMEs), and most of those particles escape all the way out past
the planets of our solar system. Sometimes, though, particles fall back down, but only if they're below the Sun's Alfvén
surface --- named after Nobel-Prize-winning physicist Hannes Alfvén. This surface has been theorized since the 1960s, but has only
been explored directly since 2021, when NASA's Parker Solar Probe plunged through it for the first time.