Gathering Interstellar Gas
2012
Redfield, Seth
Our solar system is plowing through the gas and dust that resides between the stars, the interstellar medium. The result is a bullet-shaped structure surrounding the Sun—called the heliosphere—that demarcates the balance between the outward pressure of the solar wind and the inward pressure of the surrounding gas. Every day, the heliosphere encounters a mass equivalent to Mount Everest, of what is often referred to as empty space, but which actually consists of atoms (mostly hydrogen), molecules, and dust. Some of that material is trapped at the nose of the heliosphere, some is diverted around it, and some passes right through it. On page 1291 of this issue, McComas et al. (1) present a new view of the heliosphere based on recent measurements by instruments onboard the Interstellar Boundary Explorer (IBEX) spacecraft (2) of those interstellar atoms that have passed through the heliosphere and traveled into the inner solar system.
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