For more than thirty years, our understanding of Uranus relied on data collected by the Voyager 2 probe that flew by this giant icy planet in 1986. The information collected revealed several fascinating aspects of the planet: a strange, misaligned magnetic field with its rotation, and unusual radiation belts which are full of energetic electrons. However, a new study challenges these findings and suggests that what we thought we knew might be based on an anomalous snapshot in time. This analysis challenges our vision of this distant planet and could thus change our knowledge about it.
An observation marked by a rare event
Voyager 2 was the first and so far only mission to explore Uranus up close. The overview, carried out in January 1986helped collect crucial data on Uranus' magnetosphere, a magnetic field created by the movement of materials inside its core. These measurements revealed a strange magnetic field, misaligned with the rotation of the planet, and particularly intense radiation belts.
However, more recent analysis of the data revealed that the probe's observations may not represent the normal state of Uranus. Indeed, this could be linked to the solar wind, a flow of charged particles coming from the Sun which interacts with the magnetosphere of the planets and can cause disturbances. A rare explosion of solar winda phenomenon where the solar wind strikes the magnetosphere of a planet very violently, would thus have taken place just before Voyager 2 passed. This explosion would then have temporarily distorted the magnetic field of Uranus, disrupting the measurements taken by the probe.
If the probe had flown over Uranus a few days earlier, it would have observed a much more stable magnetic field and more representative of the planet under normal conditions.
What we thought we knew
During the Voyager 2 mission, scientists observed particularly intense electronic radiation belts around Uranus, almost as powerful as those of Jupiter. However, another surprising observation was made: the planet's magnetosphere was almost empty of plasma in some areas. Plasma is a type of matter composed of charged particles that is essential for the proper functioning of the magnetosphere.
This lack of plasma led researchers to a surprising conclusion: Uranus' five large icy moons, including Titania and Oberon, were probably geologically inactive. In other words, these moons did not produce water ions, which could have indicated the presence of oceans hidden beneath their surface.
However, the new analyzes show that this conclusion could be incorrect. In fact, the absence of plasma and the anomaly of the radiation belts would only be the result of the temporary deformation of the magnetic field caused by the explosion of the solar wind. The energy of this wind drove the usual plasma from Uranus' magnetosphere and moved it towards the radiation belts, creating the illusion of a strange magnetic field. This means that the icy moons of Uranus could be more geologically active than previously thought and that it is possible that oceans beneath their surfaces exist, but have not been detected due to disturbances.
A planet still full of mysteries
Uranus remains one of the most enigmatic planets in our Solar System. Although the Voyager 2 probe provided valuable information, this new study shows that our knowledge of this planet may be based on biased data obtained during a rare phenomenon. This discovery highlights the importance of questioning scientific results in light of new information.
Researchers hope that future exploration missions dedicated to Uranus will provide answers to questions left unanswered by these new analyses. This would allow us to better understand this fascinating planet and deepen our knowledge of its system, its moons and its geological characteristics.
