Source: Visit websiteFor two decades now, the iconic twin Voyager spacecraft have been quietly overturning everything we thought we knew about the boundary between our solar system and interstellar space
For all of humanity⁘s millennia of staring at the stars and decades of launching probes to explore our universe, only two spacecraft carrying working instruments have ever managed to escape the bubble of space governed by our sun .
The twin Voyager spacecraft launched in 1977 on an epic tour of the outer planets; both swung past Jupiter and Saturn while Voyager 2 added Uranus and Neptune to the itinerary. The two spacecraft have trekked ever outward since, and several of their instruments have continued observations despite the challenges of aging technology and waning power supplies . And on December 16, 2004, Voyager 1 reached the termination shock, the beginning of its yearslong transition to interstellar space . Voyager 2 crossed the same threshold in 2007. In the years since, the spacecraft have been providing humanity⁘s only direct taste of what lies on the outskirts of and beyond the bubble of the sun⁘s influence on space, an area that scientists call the heliosphere.
⁘We know now how little we know about the heliosphere,⁘ says Merav Opher, a space physicist at Boston University. ⁘It⁘s way more complex, way more dynamic than we thought.⁘
Here⁘s what scientists do know: we everyday Earthlings may simplistically think of the sun as a compact distant ball of light, in part because our plush atmosphere protects us from our star⁘s worst hazards. But in reality the sun is a roiling mass of plasma and magnetism radiating itself across billions of miles in the form of the solar wind, which is a constant stream of charged plasma that flows off our star. The sun⁘s magnetic field travels with the solar wind and also influences the space between planets. The heliosphere grows and shrinks in response to changes in the sun⁘s activity levels over the course of an 11-year cycle .
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