Voyager 2 was unlucky. It flew past Uranus at a very bad time

Much of what we know so far about the seventh planet from the Sun comes from the passage of a space probe NASA Voyager 2 in 1986. Scientists took a second look at data obtained during the historic mission.

It turned out that the probe flew by the planet just a few days after the powerful one storm solar radiation, which significantly disturbed the observations. – The spacecraft approached Uranus in conditions that occur only about four percent of the time. The flyby took place during the maximum intensity of the solar wind, said lead author Jamie Jasinski, a physicist at NASA's research institute.

As noted in the latest study, such difficult weather conditions in space led to erroneous conclusions about the icy world of Uranus, and especially its magnetosphere. The magnetosphere is the area around the planet that protects it from the solar wind, a stream of plasma emanating from the Sun. Understanding how magnetospheres around other planets work not only helps researchers plan science missions, but also provides information about how “our” magnetosphere works.

Scientists have now discovered that during the storm, the solar wind hit Uranus with great force, resulting in it “squashing” its magnetosphere to 20 percent of its normal volume. – We would have observed a much larger magnetosphere if Voyager 2 had arrived a week earlier, Jasinski pointed out. This would likely show that it is similar to the magnetosphere of Jupiter, Saturn and Neptune, the other giants in the solar system.

See also: More moons of Uranus and Neptune discovered

As the scientist explained, “the plasma environment of the magnetosphere for any planet usually consists of plasma coming from the solar wind, the moons and the planet's atmosphere.” Meanwhile, the data sent back by Voyager 2 left the false impression that Uranus' magnetosphere is almost devoid of plasma.

Plasma, i.e. ionized matter with a gas-like state of matter, is a common component of the magnetospheres of other planets, so its low concentration in the case of Uranus was puzzling. “We didn't observe plasma from the solar wind or the moons, and what we did find was very faint,” Jasinski said.

Uranus, which orbits nearly 20 times farther from the Sun than Earth, has 28 known moons and two sets of rings. The spacecraft's observations suggested that its two largest moons – Titania and Oberon – often lie outside the magnetosphere.

However, the new study shows that they remain inside this protective bubble. “We think they are prime candidates for hosting oceans of liquid water because of their large size compared to other moons,” noted Corey Cochrane, co-author of the study published Monday in the journal Nature Astronomy.