See the pink glow of Uranus in its full 3D glory
Fresh observations from the James Webb Space Telescope show how vivid auroras emerge through Uranus’s tilted magnetic field
Multiple views of Uranus, as seen by the James Webb Space Telescope’s NIRSpec instrument during a 15-hour period in late January 2025. The ice giant polar poles appear as pink spots, and help track temperatures and dynamics in the planet’s upper atmosphere.
ESA/Web, NASA, CSA, STSCI, P. Tiranti, H. Melin, M. Zamani (ESA/Web)
Uranus has been criminally overlooked among the planets of the solar system. Like its outer Solar System neighbor, Neptune, this “ice giant” world is so far from the Sun (and so faint to see) that we’ve only sent one spacecraft, NASA’s Voyager 2, its way — and that was more than 40 years ago.
That single flyby, completed in late January 1986, could barely probe the depth of the planet. And this happened right after the solar storm Crushed Uranus’s magnetic fieldVoyager 2’s observations limited what scientists could learn about it.
Yet despite Uranus’s bland appearance, it may be key to solving many planetary puzzles. It is one of two major planets orbiting the Sun that rotate in retrograde (clockwise) motion – and it is the only planet with such an extreme axial tilt, in which its axis of rotation is nearly perpendicular to its orbital motion. In other words, Uranus revolves around our star like a spinning top that is tilted up and rotating backward. This astronomical obliquity probably came from a giant planetary collision with Uranus early in the Solar System’s history, and caused the ice giant’s strange season that spanned 42 Earth years. It may also have helped create Uranus’s unbalanced, chaotic magnetic field, which is misaligned with the planet’s center of gravity and spin.
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Yet as strange as Uranus is in some ways, in other respects it appears to be more typical: The planetary systems that astronomers have found around other stars are filled with so many worlds that resemble Uranus in size and mass that this class of planet is probably the most common in the galaxy. So, if we want to understand how planets form and evolve, whether here or across the galaxy, we probably need to understand Uranus better.
That’s why new observations of the giant ice mass by NASA’s James Webb Space Telescope (JWST) offer more than pretty pictures. Performed by an international team and led by Ph.D.s in planetary science. Paola Tiranti did it. student at Northumbria University in England, the observations were published In geophysical research paper On 19 February. Previous JWST observations of the planet have unveiled a new moon, charted the world’s microscopic rings, and more.
Capturing nearly an entire Uranian day, the new JWST data map the temperature and density of charged particles moving through the ice’s vast ionosphere, a high region of the atmosphere where auroras form and interact with the solar wind, as well as Uranus’s bizarre magnetic field. Data—which specifically detects the abundance of H3+An ion – made up of three hydrogen nuclei – creates the best three-dimensional map of the planet’s upper atmosphere yet.
“With Webb’s sensitivity, we can trace how energy moves upward through the planet’s atmosphere and even see the effects of its unbalanced magnetic field,” Tiranti said. a statement.
He said JWST has a good view of how Uranus’s auroras extend across and through the lower atmospheric layers. “Webb has now shown us how deep into the atmosphere those impacts reach. By revealing the vertical structure of Uranus in such detail, Webb is helping us understand the energy balance of ice giants. This is an important step toward characterizing the giant planets beyond our solar system.”
A mystery that was confirmed by observations but unfortunately not resolved concerns the particularly falling temperatures of Uranus. For decades, scientists have found that the ice giant’s upper atmosphere has been cooling unexpectedly — and these latest measurements show that trend is still continuing. JWST observed an average temperature in Uranus’s upper atmosphere of about 150 degrees Celsius – which is lower than values ​​seen in previous observations.
The planet’s auroras appear as pink, glowing patches that extend above the visible edges of Uranus’s atmosphere in JWST images, which also capture the ice giant’s delicate ring systems and the bright clouds surrounding its polar caps. But the rings and clouds of Uranus in these images are mostly just fascinating, says Heidi Hammel, a JWST interdisciplinary scientist at the Association of Universities for Research in Astronomy, who was not involved in this work. Auroras are real scientific stars.
“These auroral detections are extremely important because they are a direct expression of the planet’s internal magnetic field,” Hamel says. “We really don’t have any other way to probe the magnetic field remotely without a spacecraft.”
American astronomer still hope to send another spaceship to uranus in the coming yearsBut tight federal budgets – and the tight timelines required for energy-efficient interplanetary travel – may make such missions inconveniently far into the future. For now, scientists may have to settle for JWST’s distant-but-stunning views.
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