Science1 publisher2 min readPublished
Smile's ultraviolet camera passes its first test with a daylight aurora over the North Pole
Smile, a European-Chinese mission, began science operations after its ultraviolet camera caught a daylight aurora over the North Pole. The July frames show the hardware works, and findings on solar particles and Earth's magnetic field still await more data and a recalibrated X-ray imager.
The Scientist · Science desk
Drafted by a language model from the sources cited here and checked against its claim ledger before publication. How we use AISend a correction
What happened
- The images date from July 2026, two weeks after scientists first switched on the Ultraviolet Aurora Imager, and show the instruments working as intended.
- They show a ring of charged particles coiling around the North Pole and covering about a third of Earth's sunlit side.
- Smile launched on May 19 into a highly elliptical orbit reaching about 75,000 miles above the North Pole, with three years of observation planned.
- Besides the ultraviolet camera, the spacecraft carries three instruments that detect X-rays, magnetic fields and light ions.
Compiled by The ScientistSomething wrong?How this is made
Why it matters
- capability Ultraviolet imaging from high above the pole lets researchers follow auroral activity on Earth's sunlit side, where human eyes see none, over unbroken stretches of nearly two days.
- constraint Until ground teams remove the excess light the soft X-ray detector picks up when aimed at Earth, the mission's X-ray view of Earth trails its ultraviolet one.
- constraint Anyone expecting a whole-planet account of solar particles meeting the magnetic field will have to wait for the long record, because the first release shows working hardware and no findings.
From the ground, auroras are something you see at night, and they rarely appear far from the poles [6]. They form when charged particles from the Sun slide along Earth's magnetic-field lines and hit light-emitting molecules near the poles [7]. Smile's camera records in ultraviolet. Its first frames put the auroral ring on the sunlit half of the planet, where human eyes do not see one [3][6].
From its orbit, Smile can watch the North Pole for 45 hours at a time, a figure Live Science describes as record-breaking [9]. The spacecraft is a joint project of the European Space Agency and the Chinese Academy of Sciences [1].
The pictures are older than the release date suggests. The images shared on Sept. 30 were captured in July [13][4], so two to three months passed between exposure and publication [2]. Counting from the May 19 launch, the mission took about four and a half months to reach formal science operations [1].
According to Live Science, the images establish that the instruments work as they should and that the mission could officially begin [5]. The outlet reports no scientific finding from them yet. The thing a single set of July frames cannot tell you is how the auroral ring responds as the stream of particles from the Sun changes. That question needs a long record, and Smile has three years of observing planned [8].
The X-ray instrument is behind. Scientists pointed the soft X-ray imager at Cassiopeia A, a supernova remnant about 11,000 light-years away, and the camera worked [11][12]. Aimed at Earth, its detector still picks up a bit too much light, and scientists on the ground have more calibration to do [12].
In my view, Sept. 30 is a commissioning milestone. A whole-planet account of how solar particles meet Earth's magnetic field would draw on all of Smile's instruments over many 45-hour passes [10][9]. So far the published evidence is one ultraviolet camera working as designed and an X-ray camera still being tuned [5][12].
What to watch
- Whether ground calibration removes the excess light the soft X-ray imager picks up when aimed at Earth, and when its first clean Earth images are released.
- The first published results from the ultraviolet imager that tie changes in the auroral ring to the particles arriving from the Sun.
- Data from the magnetic-field and light-ion instruments, which the first release did not include.