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Most assessments of global warming use 1850-1900 as a baseline, but researchers have now established a new pre-industrial reference by using Antarctic ice cores to estimate the average temperature before 1700

Experiments show that illuminating the underside of a decoy seal reduces attacks by great white sharks, revealing a possible strategy to protect surfers and swimmers

Experiments show that illuminating the underside of a decoy seal reduces attacks by great white sharks, revealing a possible strategy to protect surfers and swimmers

Voyager 2 flew by Uranus in 1986, giving us our only up-close look at the planet – but unusual space weather just before the craft arrived has given us a misleading idea about the planet’s magnetic field

Voyager 2 flew by Uranus in 1986, giving us our only up-close look at the planet – but unusual space weather just before the craft arrived has given us a misleading idea about the planet’s magnetic field

4 min read

Preparations for Next Moonwalk Simulations Underway (and Underwater) NASA’s Voyager 2 captured this image of Uranus while flying by the ice giant in 1986. New research using data from the mission shows a solar wind event took place during the flyby, leading to a mystery about the planet’s magnetosphere that now may be solved.NASA/JPL-Caltech

NASA’s Voyager 2 flyby of Uranus decades ago shaped scientists’ understanding of the planet but also introduced unexplained oddities. A recent data dive has offered answers.

When NASA’s Voyager 2 spacecraft flew by Uranus in 1986, it provided scientists’ first — and, so far, only — close glimpse of this strange, sideways-rotating outer planet. Alongside the discovery of new moons and rings, baffling new mysteries confronted scientists. The energized particles around the planet defied their understanding of how magnetic fields work to trap particle radiation, and Uranus earned a reputation as an outlier in our solar system.

Now, new research analyzing the data collected during that flyby 38 years ago has found that the source of that particular mystery is a cosmic coincidence: It turns out that in the days just before Voyager 2’s flyby, the planet had been affected by an unusual kind of space weather that squashed the planet’s magnetic field, dramatically compressing Uranus’ magnetosphere.

“If Voyager 2 had arrived just a few days earlier, it would have observed a completely different magnetosphere at Uranus,” said Jamie Jasinski of NASA’s Jet Propulsion Laboratory in Southern California and lead author of the new work published in Nature Astronomy. “The spacecraft saw Uranus in conditions that only occur about 4% of the time.”

The first panel of this artist’s concept depicts how Uranus’s magnetosphere — its protective bubble — was behaving before the flyby of NASA’s Voyager 2. The second panel shows an unusual kind of solar weather was happening during the 1986 flyby, giving scientists a skewed view of the magnetosphere.NASA/JPL-Caltech

Magnetospheres serve as protective bubbles around planets (including Earth) with magnetic cores and magnetic fields, shielding them from jets of ionized gas — or plasma — that stream out from the Sun in the solar wind. Learning more about how magnetospheres work is important for understanding our own planet, as well as those in seldom-visited corners of our solar system and beyond.

That’s why scientists were eager to study Uranus’ magnetosphere, and what they saw in the Voyager 2 data in 1986 flummoxed them. Inside the planet’s magnetosphere were electron radiation belts with an intensity second only to Jupiter’s notoriously brutal radiation belts. But there was apparently no source of energized particles to feed those active belts; in fact, the rest of Uranus’ magnetosphere was almost devoid of plasma.

The missing plasma also puzzled scientists because they knew that the five major Uranian moons in the magnetic bubble should have produced water ions, as icy moons around other outer planets do. They concluded that the moons must be inert with no ongoing activity.

Solving the Mystery

So why was no plasma observed, and what was happening to beef up the radiation belts? The new data analysis points to the solar wind. When plasma from the Sun pounded and compressed the magnetosphere, it likely drove plasma out of the system. The solar wind event also would have briefly intensified the dynamics of the magnetosphere, which would have fed the belts by injecting electrons into them.

The findings could be good news for those five major moons of Uranus: Some of them might be geologically active after all. With an explanation for the temporarily missing plasma, researchers say it’s plausible that the moons actually may have been spewing ions into the surrounding bubble all along.

Planetary scientists are focusing on bolstering their knowledge about the mysterious Uranus system, which the National Academies’ 2023 Planetary Science and Astrobiology Decadal Survey prioritized as a target for a future NASA mission.

JPL’s Linda Spilker was among the Voyager 2 mission scientists glued to the images and other data that flowed in during the Uranus flyby in 1986. She remembers the anticipation and excitement of the event, which changed how scientists thought about the Uranian system.

“The flyby was packed with surprises, and we were searching for an explanation of its unusual behavior. The magnetosphere Voyager 2 measured was only a snapshot in time,” said Spilker, who has returned to the iconic mission to lead its science team as project scientist. “This new work explains some of the apparent contradictions, and it will change our view of Uranus once again.”

Voyager 2, now in interstellar space, is almost 13 billion miles (21 billion kilometers) from Earth.

News Media Contacts

Karen Fox / Molly Wasser
NASA Headquarters, Washington
202-358-1600
karen.c.fox@nasa.gov / molly.l.wasser@nasa.gov  

Gretchen McCartney
Jet Propulsion Laboratory, Pasadena, Calif.
818-393-6215
gretchen.p.mccartney@jpl.nasa.gov

2024-156

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Details Last Updated Nov 11, 2024 Related Terms

• Voyager 2
• Heliophysics
• Jet Propulsion Laboratory
• Magnetosphere
• Solar Wind
• Uranus
• Uranus Moons

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Climate change is a huge topic and often debated across the world. We continue to burn fossil fuels and ignore our charge toward human driven climate change but while our behaviour never seems to improve, something else does! For the last few decades we have been pumping chlorofluorocarbons into the atmosphere causing a hole in the ozone layer to form. Thanks largely to worldwide regulation changes and a reduction in the use of these chemicals, the hole it seems is finally starting to get smaller. 

The ozone layer is the protective shield in Earth’s stratosphere. It’s about 15 to 35 kilometres above the Earth and its presence helps to protect us by absorbing harmful ultraviolet radiation. The region is mostly ozone composed of three oxygen molecules and it filters out the UV-B and UV-C radiation which can lead to skin cancer, cataracts and can even damage parents crops. The rest of the atmosphere is composed mostly of nitrogen gas (78%), oxygen (21%) and a few other gasses making up the remaining 1%. 

A view of Earth’s atmosphere from space. Credit: NASA

In the late 20th century scientists found that certain chemicals like the well known chlorofluorocarbons (CFC’s) were slowly destroying the layer. This resulted in seasonal holes appearing in the ozone especially over Antarctica. In 1987, the Montreal Protocol international treaty was signed to curb the global release of CFC’s and other ozone harmful gas. 

Just recently, a team of scientists from NASA and the National Oceanic and Atmospheric Administration (NOAA) have confirmed that the hole in the ozone layer over the south pole was relatively small compared to previous years. During the month of September to October, when the ozone depletion process is at its peak, it was the 7th smallest hole since 1992. An average season sees an incredible 20 million square kilometres of ozone depletion. The teams data even suggests the layer could fully recover by 2066. 

To collect the data the team uses a number of systems. A number of satellites (Aura, NOAA-20, NOAA-21 and Suomi NPP) are used to collect data from orbit. In addition they use weather balloons which are launched from the South Pole Baseline Atmospheric Observatory to directly measure ozone concentrations. 

Geostationary orbits are where telecommunication satellites and other monitoring satellites operate. This image shows one of the NOAA’s Geostationary Operational Environmental Satellites. Image Credit: NOAA.

The measurements are captured as Dobson Units. One Dobson Unit is equivalent to the number of ozone molecules that would be needed to create a layer of pure ozone 0.01 millimetres thick. Of course temperature and pressure would effect this so the measurement is based on a layer at 0 degrees Celsius and 1 atmosphere (the average pressure of atmosphere at surface of Earth.) In 2024, the measurement in October 2024 was 109 Dobson Units in comparison to the lowest ever value of 92 Dobson Units in 2006. 

The Montreal Protocol certainly seems to be making a difference seeing a significant and continuous decline in CFCs. This, along with an infusion of ozone from north of Antarctica have combined to reverse the depletion. 

Source : Ozone Hole Continues Healing in 2024

The post Good News, the Ozone Layer Hole is Continuing to Shrink appeared first on Universe Today.

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