When NASA's Voyager 2 spacecraft flew by Uranus in 1986, scientists got their first close glimpse of the giant icy planet. Alongside the discovery of new moons and rings, a puzzling new mystery faced scientists. The energetic particles around Uranus defied their understanding of how magnetic fields trap particle radiation. The cause of that special mystery is a cosmic coincidence, according to a new study. Just before Voyager 2's flyby, Uranus was found to have been affected by an unusual type of space weather that crushed and dramatically compressed the planet's magnetic field. Its magnetosphere.
The first panel of this artist's concept depicts how Uranus' magnetosphere operated before NASA's Voyager 2 flyby. The second panel shows that an unusual type of solar weather occurred during the 1986 flyby, giving scientists a biased view of the magnetosphere. Image credit: NASA/JPL-Caltech.
The planetary magnetosphere (the region around a planet dominated by its magnetic field) influences the environment around the planet, and understanding its properties is important for mission planning.
Voyager 2's close encounter of Uranus reveals a unique magnetosphere that is highly asymmetric and appears to lack plasma, a common element in the magnetospheres of other planets, and has an unusually strong band of high-energy electrons It became.
The signatures from this single measurement have since been used as the basis for understanding Uranus's magnetic field, but these anomalies have been difficult to explain without complex physics.
“If Voyager 2 had arrived just a few days earlier, we would have seen a completely different magnetosphere on Uranus,” said Dr. Jamie Jasinski, a researcher at NASA's Jet Propulsion Laboratory.
“The spacecraft observed Uranus in a situation that has a probability of only about 4%.”
Jasinski and his colleagues reanalyzed Voyager 2 data before the flyby and found that the spacecraft encountered Uranus shortly after a violent solar wind event that ejected streams of charged particles from the Sun's atmosphere.
This compressed Uranus's magnetosphere, creating a condition that only occurs 4% of the time.
In this state, we see a plasma-free magnetosphere with highly excited electron emission bands.
The authors suggest that two magnetospheric cycles may exist during solar minimum due to variations in Uranus' solar wind.
Additionally, the chances of Uranus' outermost major moons, Titania and Oberon, orbiting outside the magnetosphere may be very low, giving scientists the possibility of detecting an underground ocean without interference from the magnetosphere. There is.
“The 1986 flyby was full of surprises, and we were looking for an explanation for its unusual behavior,” said Dr. Linda Spilker, also of NASA's Jet Propulsion Laboratory.
“The magnetosphere measured by Voyager 2 is just a snapshot in time.”
“This new study explains some of the apparent contradictions and will once again change our view of Uranus.”
of findings Published in today's magazine natural astronomy.
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JM Jasinski others. Unusual conditions in Uranus' magnetosphere during Voyager 2's flyby. Nat Astronpublished online on November 11, 2024. doi: 10.1038/s41550-024-02389-3
Source: www.sci.news
