July 29, 2014
NASA X-Ray Instrument Settles Interstellar Debate
This animation illustrates solar wind charge exchange in action. An atom of interstellar helium (blue) collides with a solar wind ion (red), losing one of its electrons (yellow) to the other particle. As it settles into a lower-energy state, the electron emits a soft X-ray.
Credit: NASA Goddard Space Flight Center