California
Uranus is not what astronomers have thought it to be for the last several years. Our initial perception of the planet is based on data collected by Voyager 2. In 1986, when the mission flew past Uranus, it observed its magnetic field which appeared to be messy, off-centre and unusual.
This was very different from everything else that has been observed in the solar system. Astronomers have been trying to dive into the mysterious past of the planet and working to understand what makes its magnetic field such a hot mess.
However, a study has now raised questions over everything Voyager beamed back about Uranus. Space plasma physicist Jamie Jasinski of NASA's Jet Propulsion Laboratory at the California Institute of Technology says that the planet might not have an extreme magnetospheric environment as believed.
Jasinski and his team have discovered that at the time Voyager 2 flew by Uranus, it was likely battling intense solar activity, which was messing with the planet.
He told ScienceAlert that he looked at the solar wind data at Uranus and "saw that Voyager 2 measured a dramatic increase in the solar wind dynamic pressure just before the flyby".
Also Read: Experts stumble upon a crime scene in space. Who committed it and when?
"I realised that the magnetosphere must have been squashed to 20 per cent of its volume just before the flyby happened, which would have affected the discoveries we made with Voyager 2!," Jasinski said.
Voyager 2 mission and its data
Scientists say that since Uranus is extremely far away, it has been hard to learn about it. Voyager 2's measurements are the best and the closest observations of the planet to date. But solar system is not a static place and things are at the mercy of the vagaries of the space weather at a certain time.
Uranian magnetosphere had intense radiation belts and much less plasma than was expected, based on data about the other planets.
Jasinski, who earlier worked on NASA's MESSENGER mission, which studied the planet Mercury, observed that intense solar activity sometimes "completely eroded the entire magnetic field". This led him to wonder if the same could be the case with Uranus.
"The Voyager 2 flyby of Uranus lasted just five days, so I thought we may have observed Uranus at just the wrong time," he said.
The researchers again studied Voyager 2's data and found that the dynamic solar wind pressure had increased a week before the flyby.
The observations led the team to conclude that if the solar wind was flowing at its normal rate, then Uranus's magnetic field would be similar to the magnetic fields of the other gas giants, such as Jupiter, Saturn, and Neptune.
The latest discovery means that the assumption that the interior of Uranus, where the magnetic field is generated, was unique in the Solar System, might be flawed.