Pale white streaks have been observed weaving through the northern lights, presenting a new atmospheric puzzle. These eerie glows have been captured alongside traditional red and green auroras, but experts suggest they are not auroras themselves. Instead, they may share similarities with the purplish phenomenon known as Strong Thermal Emission Velocity Enhancement (STEVE). Scientists remain uncertain about what causes these white lights to form in specific regions. The discovery has prompted further investigation into the underlying mechanisms of these unexplained emissions.
White Glows Identified in TREx Mission Data
According to research published in Nature Communications, the white streaks were first identified by scientists at the University of Calgary using the Transition Region Explorer (TREx) mission. TREx, a network of low-light cameras monitoring Earth’s near-space environment, captured full-colour images that revealed these unexpected formations. Unlike other auroral imagers, which focus on specific wavelengths of red and green light, TREx detected broad-spectrum emissions.
Emma Spanswick, a space physicist at the University of Calgary, recalled, while talking to Science News, noticing an unusual grey-white patch in 2023 while reviewing auroral images. A thorough search of past TREx data uncovered 30 instances of these white-laced auroras in Saskatchewan from 2019 to 2023. Some of the formations extended for hundreds of kilometres, appearing either alongside existing auroras or in regions where colourful displays had faded.
Possible Links to STEVE and Atmospheric Heating
Spectral analysis confirmed that these white lights result from continuum emissions, where light is emitted across multiple wavelengths. This distinguishes them from traditional auroras, which arise when charged particles excite atmospheric atoms, producing specific colours. The emission pattern closely resembles that of STEVE, a fast-moving plasma band that creates purplish streaks in the sky.
Speaking to Science News, Claire Gasque, a space physicist at the University of California, Berkeley, noted that while the patchy nature of these white lights differs from the structured arc of STEVE, they may share similar origins. Researchers are now focused on identifying the forces responsible for heating atmospheric particles to create these glows. The precise cause of the phenomenon remains unknown, leaving scientists with more questions about the complexities of auroral activity.
