Something strange happened during Voyager 2’s flyby of Uranus in 1986.

Recent analysis of Voyager 2 data reveals surprising details about its passage through Uranus 38 years ago, showing a magnetosphere distorted by the solar wind.

The peculiar magnetosphere of Uranus

In 1986, Voyager 2 discovered that Uranus’s magnetosphere, the region in which its magnetic field dominates, is different from those of other planets. Unlike other magnetospheres, it did not contain plasma and had powerful energetic electron belts. Recent analysis suggests that these unique observations were caused by the solar wind, which altered the magnetosphere just before the flyby.

A research team led by Jamie Jasinski of NASA and Caltech concluded that this distortion was due to an intense burst of particles from the Sun compressing the magnetosphere just as Voyager 2 passed nearby. “If we had come a week earlier, we would have seen something completely different,” says Jasinski.

An unusual phenomenon on an unusual planet

The team estimates that such compression of Uranus’ magnetosphere occurs only 4% of the time. This means that in most cases, Uranus’ magnetosphere is not that extreme. Additionally, during solar minimum, a planet may experience alternating periods of solar wind disturbances due to its high inclination relative to its orbital plane, which affects how its magnetosphere interacts with the solar wind.

The data suggests two cycles in Uranus’s magnetosphere: one that varies throughout the day and one that is driven by changing solar wind conditions. Such events were only documented thanks to Voyager 2, the only spacecraft to visit Uranus and Neptune.

Uranus and the possibility of the existence of oceans on its satellites

The new analysis also concludes that the outer moons Titania and Oberon orbit within Uranus’ magnetosphere, making it easier to detect possible subsurface oceans because the magnetic field can interact with fluids beneath the moons’ surfaces. Titania and Oberon, due to their size, could retain heat, which increased the likelihood of retaining liquid water.

Jasinski mentions that Titania and Oberon are prime candidates for underground oceans because their size allows them to retain heat, reducing the likelihood of completely freezing. These results open the possibility for future missions to Uranus that could confirm the presence of water on these moons.

Legacy of Voyager 2

Nearly four decades later, Voyager 2 continues to provide key information about Uranus. The mission, now in interstellar space and billions of kilometers from Earth, continues to operate thanks to NASA’s energy-saving measures. Their discoveries have increased scientific interest in Uranus, a planet with as-yet-unexplored features that experts want to explore further.

The science team hopes that over time, this data will help guide future missions to Uranus. In the meantime, they will continue to extract all the information they can from the data collected by Voyager nearly 40 years ago.

This article was translated from Gizmodo US by Thomas Handley. You can find the original version here.