The sun, in motion through our galaxy, is constantly emitting solar winds, which were previously thought to form a “bubble”called the heliosphere that trails behind the sun in a similar fashion to the formation of the tail of a comet. A new NASA-funded study, however, has found that this is not the case.
Rather, the sun is emitting these winds in two jets originating from the poles of the sun. This means the heliosphere is not shaped like a comet with a tail, but like a crescent in a relatively short tail behind the sun itself.
The recent discovery is important for several reasons. Studying these close-to-home jets, for example, could yield more information on ones found throughout the universe, as they are very similar. “Everyone’s assumption has been that the shape of the heliosphere was molded by the flow of interstellar material passing around it,” said Merav Opher, an astronomer at Boston University. “Scientists thought the solar wind flowing down the tail could easily pull the magnetic fields in the heliosphere along as it flowed by, creating this long tail. But it turns out the magnetic fields are strong enough to resist that pull – so instead they squeeze the solar wind and create these two jets.”
NASA’s own Voyager 1 provided these observations that in turn, yielded the new simulation of the heliospheric shape. The new model’s proposal, however, is expected to be controversial, as many scientists continue to work with the accepted comet-like model of the heliosphere.
Although scientists do not fully understand the physics of these emissions yet, further study of our own sun and its jets, which are far closer and far easier to study, could tell us a lot more about larger, more distant stars, and about the formation and death of stars. Jim Drake, a scientist at the University of Maryland states, “If we’re right about all of this, it gives us a local test bed for exploring some very important physics.”
