Our picture of Uranus has not advanced substantially beyond being the featureless blue ball captured by Voyager 2 instruments in 1986.
But last year, while reviewing NASA files, two planetary scientists noticed something that previous analyzes had missed : a fault in Uranus’ magnetic field as the spacecraft passed through a kind of magnetic bubble .
The new results , which appeared last summer in Geophysical Research Letters , reveal a much more fascinating Uranus than we thought. The Voyager 2 flight was only able to detect this structure for 60 seconds of the 45 hours it took to collect data . It appeared as a very fast signal up and down in the magnetometer data.
Gina DiBraccio and Daniel Gershman of NASA’s Goddard Space Flight Center are two of these researchers. Motivated by the community’s growing interest in the outermost planets, they spent hours manually processing thirty-year data in a new way. And then they saw the plasmoid.
A plasmoid is a coherent structure of plasma confined by a magnetic field. Plasmoids have been proposed as a natural explanation for globular rays, magnetic bubbles in the magnetosphere, and other objects in comet tails, in the wind, in the solar atmosphere, or in the heliospheric current.
Scientists believe that a planet’s magnetic fields can protect it, preventing the solar wind from destroying the atmosphere. However, these fields can also generate escape options. This leads scientists to pay special attention to a planet’s magnetic fields to understand how its atmosphere behaves. The magnetic burp Voyager 2 passed through was a first for Uranus .
It looks quite similar to those seen on Saturn or Jupiter, but with a greater mass: this plasmoid formed a cylinder approximately 22,000 times larger than Earth: 204,000 kilometers long and 400,000 kilometers wide .
Scientists are particularly interested in studying plasmoids because these structures can extract charged particles from a planet’s atmosphere and throw them into space. If you change the atmosphere of a planet, you change the planet itself. More such discoveries could remain on file, awaiting further analysis .