File:Solar System Bubble.jpg

English: As the solar wind flows from the sun, it creates a bubble in space known as the heliosphere around our solar system. The heliosphere is the region of space under the influence of our sun. The interstellar medium, the matter that fills the local region of our galaxy, is forced to flow around the heliosphere. It disturbs the solar wind so much as to create a secondary bubble around the heliosphere known as the heliosheath, which is filled with heated, slower solar wind.

Scientists on the Cassini mission used the Ion and Neutral Camera sensor on the Magnetospheric Imaging Instrument to look at the interaction of these plasma bubbles with the interstellar medium. The scientists also looked at how the heliosphere and heliosheath move through the interstellar medium together. The sensor on Cassini detects hot particles known as energetic neutral atoms at high energies, complementary to instruments on the NASA Interstellar Boundary Explorer mission.

The shape of our solar system moving through the interstellar medium was previously thought to be comet-shaped, with a head pointed into the stream, and a tail flowing downstream. New observations show the shape actually resembles something more like a slippery ball (the hot particles that exert pressure) moving through smoke (the interstellar magnetic field). As the "ball" moves through the "smoke," the smoke bends and parts to let the ball through, then resumes its previous shape after the ball has passed on. At present, this is only hypothetical: New models will be motivated by these measurements, and will provide a more physically accurate basis for the interaction of the heliosphere with the interstellar medium.