Pluto's interaction with the solar wind is unique

Pluto behaves less like a comet than expected and somewhat more like a planet like Mars or Venus in the way it interacts with the solar wind, a continuous stream of charged particles from the sun.
This is according to the first analysis of Pluto’s interaction with the solar wind, funded by NASA’s New Horizons mission and published today in the Journal of Geophysical Research – Space Physics by the American Geophysical Union (AGU).
Using data from the Solar Wind Around Pluto (SWAP) instrument from the New Horizons July 2015 flyby, scientists have for the first time observed the material coming off of Pluto’s atmosphere and studied how it interacts with the solar wind, leading to yet another “Pluto surprise.”

https://www.nasa.gov/feature/pluto-s-interaction-with-the-solar-wind-is-unique-study-finds