May 11, 2012
Speed Of The Sun ‘Shockingly’ Slower Than Believed
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A team of NASA researchers has uncovered new data showing that the sun is moving more slowly through our galaxy than previously believed -- a discovery that suggests a shock wave believed to precede the heliosphere might not actually exist, the US space agency revealed on Thursday.
According to Andrew Fazekas of National Geographic News, NASA's Interstellar Boundary Explorer (IBEX) satellite measured the speeds of various interstellar particles along the outer edges of our solar system, some 9 billion miles from the sun.
Using the information they collected and inserting it into computer models, Fazekas said that they learned that the sun is actually moving at approximately 52,000mph, or about 7,000mph slower than originally thought.
Their findings, which have been published online in the journal Science, also revealed that the actual speed of the sun means that the pressure from materials flowing around it's astrosphere is one-fourth less than expected, meaning that it is not high enough for a bow shock -- a shockwave that goes ahead of this "protective bubble" on its journey through space -- to occur, Science News writer Nadia Drake reported.
Prior to this report, lead researcher David McComas of the Southwest Research Institute (SwRI) in San Antonio, Texas told National Geographic, "all the solar system models and theories included a bow shock. Having learned for nearly three decades about it, I was literally shocked when we found it was missing."
"It's too early to say exactly what this new data means for our heliosphere. Decades of research have explored scenarios that included a bow shock. That research now has to be redone using the latest data," he added in a separate statement. "Already, we know there are likely implications for how galactic cosmic rays propagate around and enter the solar system, which is relevant for human space travel."
The researchers used the IBEX data, as well as information collected by Voyager probes in the late 1970s, in order to show that the magnetic field in the interstellar medium is stronger than believed, thus requiring faster speeds in order to produce a bow shock. The SwRI said that their calculations were corroborated by two other, independent models, one from a group in Alabama and another originating in Moscow.
According to Fazekas, "The absence of a bow shock is significant“¦ because it may indicate that the heliosphere is actually more robust than thought. With less pressure from outside material, the boundary region isn't being compressed and therefore weakened as much as expected, which means it should better repel cosmic rays“¦ And understanding exactly how the heliosphere acts as a gatekeeper for cosmic rays could help scientists evaluate the chances for life on other worlds."