The Voyager space probes, at the outer limits of the solar system, revealed that the wispy, 30 light years wide, interstellar cloud surrounding the solar system is held together by a strong magnetic field.
By NASA FishOutofWater
"Using data from Voyager, we have discovered a strong magnetic field just outside the solar system," explains lead author Merav Opher, a NASA Heliophysics Guest Investigator from George Mason University. "This magnetic field holds the interstellar cloud together and solves the long-standing puzzle of how it can exist at all."
About 10 million years ago a cluster of supernovas erupted in the solar neighborhood raising interstellar gas temperatures to a million degrees. The cloud around the solar system is a relatively cool 6000 Celsius. Why the relatively cool local interstellar cloud known as the "local fluff" wasn't ripped apart or compressed in this heated environment was a mystery until the Voyagers discovered the strong magnetic field that holds the cloud together.
The sun's magnetic field, creates a protected bubble called the heliosphere that shields the solar system from galactic cosmic rays and interstellar clouds. The earth has a similar protective magnetic bubble called the magnetosphere. The combination of these bubbles reduce the level of radiation reaching earth, making it habitable for life. After 30 years of travel, Voyagers 1 and 2 have now entered the outer region of the heliosphere known as the heliosheath. The strong magnetic field of the "local fluff" cloud has compressed the heliosphere to a smaller volume than would have been found if the cloud had little or no magnetic field.
By NASA FishOutofWater
The size of the heliosphere is determined by a balance of forces: Solar wind inflates the bubble from the inside while the Local Fluff compresses it from the outside. Voyager's crossings into the heliosheath revealed the approximate size of the heliosphere and, thus, how much pressure the Local Fluff exerts. A portion of that pressure is magnetic and corresponds to the ~5 microgauss Opher's team has reported in Nature.
The solar system's interaction with the local interstellar cloud.
By NASA FishOutofWater