The edge of our solar system is not a smooth graceful curvature of the sun’s magnetic field, as previously believed but a “turbulent sea of magnetic bubbles,” Nasa has speculated.
The space agencies twin spacecrafts Voyageur 1 and 2 are now flying through the “heliosheath”, essentially the border between the sun’s reign and the rest of our galaxy. More than 9 billion miles from earth, the Voyageurs are sending back data suggesting that foam made of magnetic bubbles sizing 100 million miles, lines the periphery of our solar system. “The sun’s magnetic field extends all the way to the edge of the solar system,” said astronomer Merav Opher of Boston University, author of the study. “Because the sun spins, its magnetic field becomes twisted and wrinkled, a bit like a ballerina’s skirt. Far, far away from the sun, where the Voyagers are, the folds of the skirt bunch up.”
The bubbles are a result of magnetic field reorganisation as the sun’s sphere of influence depletes. According to Nasa analysis, these field lines break open to form individual structures or bubbles, and are no longer connected to the solar magnetic field.
“We never expected to find such a foam at the edge of the solar system, but there it is!” says Jim Drake, one of the researchers that worked on the new computer model developed to process Voyageur data.
This discovery, once backed by additional data from Voyageur, will be critical in understanding how we interact with the universe outside.
These findings will help in addressing protection from cosmic rays and galactic magnetism that are the contenders to influentially intrude our solar family. Physicists are already arguing the matter of how protective such a segmented shield might be. Some say the foamy nature will make it porous, thus easy to counter; others say cosmic rays could get trapped in the bubbles making them a very good barrier. “The magnetic bubbles appear to be our first line of defence against cosmic rays,” said Opher. “We haven’t figured out yet if this is a good thing or not.”
The evidence of the bubbles has been provided by primitive data from Voyager’s energy particle and flow measurements. Once analysed, the magnetic field data will be able to reveal much more with clarity.
As the spacecrafts speed through the foam, Merav Opher is expecting to learn much more about the organisations of the healiosheath. “This is just the beginning, and I predict more surprises ahead,” he said. In 1977, Voyageur 1 and 2 started their journey into deep space in the direction of the galaxy centre. Powered by natural radioactive decay, the twins have continued to serve well beyond their expected timelines. The data they record is relayed as radio messages and currently takes 16 hours to reach the earth.