"Low-Energy Cosmic Rays at the Extremes of the Heliosphere: Results from Voyager and Parker Solar Probe"

Presented by Dr. Jamie Rankin, Research Scholar and Secondary Lecturer, from Princeton University.

In 2012, during the centennial year of the discovery of cosmic rays, Voyager 1 crossed the heliopause and began making the very first in-situ observations of the surrounding interstellar medium. Joined by Voyager 2 in 2018, these twin spacecraft have revealed a surprisingly rich and previously unexplored regime that challenges long‑standing assumptions about cosmic‑ray transport and heliosphere-interstellar interactions. Meanwhile, since 2018, Parker Solar Probe has opened an entirely different frontier, venturing closer to the Sun than any spacecraft before it, directly sampling the near-Sun environment where cosmic rays are heavily modulated and standard assumptions about transport conditions have remained largely untested. This talk will highlight the new insights, discoveries, and open questions that have arisen from in-situ measurements of low-energy cosmic rays (few to hundreds of MeV) at these two heliospheric extremes and discuss their implications for our current understanding of our own global astrosphere.