A group of researchers from the University of Calgary has managed to explain for the first time the appearance of a whitish or grayish spot that is sometimes observed in the night sky next to the northern lights. This finding, published on December 30 in the journal Nature Communicationsaddresses what is known as “structured continuum emission,” which is associated with these luminous phenomena.
Dr. Emma Spanswick, lead author of the study and associate professor in the Department of Physics and Astronomy of the Faculty of Science, points out that “you see a dynamic green aurora, with hints of red in the background, and suddenly this structured emission appears , almost like a stain, with grayish or whitish tones connected to the aurora. Although this phenomenon had been mentioned in previous scientific works, it had never been adequately explained.
According to the research team, this spot is “almost certainly a heat source,” suggesting that the northern lights are more complex than previously thought. Dr Spanswick attributes the discovery to advances in camera technology, which allow both amateur photographers and scientists to capture true-colour images of the night sky.
Technological advances and their impact on research
«Everyone has noticed the advance of digital photography. Nowadays, a mobile phone can take photographs of the aurora,” says Spanswick. “That technology has permeated the commercial sensor market.” This progress has enabled deeper research into continuous emission, especially following renewed interest in the phenomenon known as STEVE (Strong Thermal Emission Velocity Enhancement), a purple luminous ribbon also seen in the sky.
The researcher explains that “there are similarities between what we are observing now and STEVE”, since the latter manifests itself as a structure of mauve or gray tone. “The spectral elevation between the two is very similar, but this phenomenon, due to its association with the dynamic aurora, is almost embedded in it, making it difficult to identify, while STEVE appears as a separate band crossing the sky ».
The study also highlights the participation of three University of Calgary students, including Josh Houghton, who was initially hired as an intern on the project. Houghton, who quickly became involved in the research, has done much of the analysis, which allowed him to participate in the publication in the journal Nature as an undergraduate student. “You have had an incredible internship experience,” Spanswick concludes, highlighting her continued work in research as part of her honors thesis before starting her master’s degree next year.
More information:
E. Spanswick et al, Association of structured continuum emission with dynamic auroras, Nature Communications (2024). DOI: 10.1038/s41467-024-55081-5
