In a major discovery that could reshape understanding of Uranus, scientists now believe Voyager 2 may have observed a rare cosmic phenomenon during its historic 1986 flyby.
NASA's Voyager 2 remains the only spacecraft to have visited Uranus, offering unique insights into the planet. During its brief five-hour pass, Voyager 2 recorded an unusually empty magnetosphere-Uranus's magnetic shield-raising questions for decades.
Dr. Jamie Jasinski from NASA's Jet Propulsion Laboratory, who led recent research on the flyby data, noted, "If Voyager 2 had arrived just a few days earlier, it would have observed a completely different magnetosphere at Uranus."
Rare Solar Event Shrinks Uranus's Magnetosphere
The emptiness Voyager 2 observed, scientists now say, likely resulted from an intense burst of solar activity just days before the spacecraft's arrival. This rare solar event, known as a co-rotating interaction region, compressed Uranus's magnetosphere to just a fifth of its usual size.
As a result, plasma that would typically fill the magnetosphere was forced inward, leaving the outer region unexpectedly sparse. These conditions occur only about 4% of the time, according to the data analyzed in the new study published in Nature Astronomy.
This unusual phenomenon also explains why the radiation belts-regions of trapped high-energy particles around Uranus-appeared so intense during Voyager's pass. The solar event intensified the belts by adding high-energy particles from the sun.
Previously, scientists struggled to explain this intense radiation since they found few plasma sources around the planet itself.
Dr. Fran Bagenal, a planetary scientist at the University of Colorado and member of the Voyager program, remarked on the findings, saying, "It explains why the density we saw was so low." The research has sparked interest in a potential NASA return mission, which could provide a clearer picture of Uranus's environment.
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