EGU LUNEX 2026 Total Solar Eclipse Campaign in Spain: Early Career Scientist Multiwavelength Observations and Outreach

The total solar eclipse of 12 August 2026, visible along a path crossing the Russian Arctic, Greenland, Iceland, Portugal, and Spain, will provide an exceptional opportunity for both scientific observations and public engagement. As part of a broader observing campaign [1] (that includes observations from various sites along the path), a group of early career scientists will conduct a set of complementary experiments aimed at obtaining scientifically useful measurements, engaging wider society, and preparing observational strategies for the 2027 total solar eclipse.

 

The optical experiments will include white light imaging of the solar corona using telescopes with different focal lengths. Our wide field setup will be used to image the corona from our observing site during totality. These observations will later be combined with measurements obtained by other sites within the broader campaign, enabling multi-site image stacking and the construction of a temporal sequence of the corona during totality [1,2]. A longer focal length setup will be used to carry out a modern version of the Einstein–Eddington experiment by measuring the apparent positional shifts of stars close to the eclipsed Sun, caused by gravitational light deflection. In addition, sky spectra will be recorded at different eclipse phases to study how the integrated sky spectrum changes as direct photospheric light is suppressed and the corona becomes visible [3,4].

 

The campaign will also include ionospheric experiments using radio observations and GNSS based measurements. Very low frequency and low frequency radio receivers will monitor stable transmitters before, during, and after the eclipse. Changes in received signal strength and propagation conditions can be used to probe eclipse driven changes in the ionosphere caused by reduced solar ionization. In parallel, GNSS data from personal phones and, where available, dedicated receivers will be collected to investigate possible changes in signal strength, positioning residuals, and ionospheric delay proxies. These measurements will be designed as a citizen science activity, allowing the public to contribute geographically distributed data.

 

The observing site and activities will be announced publicly. Outreach will include safe solar viewing, solar projection demonstrations, sunspot observations, distribution of eclipse glasses, and explanations of the science behind the experiments [2,5]. In this way, the campaign will combine eclipse science, public participation, and training for future total eclipse observations.

 

References:

[1]  Schmieder, B., Baratashvili, T., Poedts, S., Lani, A., Wang, H., Foing, B., Sansari, S., Zeegers, S., Pascual, J., Nahum, R., Nagainis, K., Gomez de Castro, A. I., and Heras, A.: Total Eclipse on August 12, 2026: observations in Spain and prediction with COCONUT, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-1542, https://doi.org/10.5194/egusphere-egu26-1542, 2026.

[2] European Space Agency, “Solar Total Eclipse 1999,” ESA Science & Technology, 1999. Available: https://sci.esa.int/web/observational-astronomy/-/38064-total-eclipse-99

[3] B. H. Foing, L. Duvet, L. Ligot, J. Oliveira, T. Beaufort, J. E. Wiik, B. Altieri, N. Henrich, S. Cravatte, and E. Maurice, “Results from the 3 November 1994 Solar Eclipse: Density and Temperature Variations in Streamers and Coronal Holes,” in The Tenth Cambridge Workshop on Cool Stars, Stellar Systems and the Sun, ASP Conference Series, vol. 154, R. A. Donahue and J. A. Bookbinder, Eds. San Francisco, CA: Astronomical Society of the Pacific, 1998, p. 1035.

[4] B. H. Foing, L. Duvet, K. Muglach, J. E. Wiik, T. Beaufort, and E. Maurice, “Polar plumes and streamers from 1994 and 1998 eclipses,” in Solar Jets and Coronal Plumes, ESA SP-421, 1998, p. 273.

[5] European Space Agency, “Solar Eclipse Index,” ESA Multimedia, 1 July 1999. Available: https://www.esa.int/ESA_Multimedia/Videos/1999/07/Solar_Eclipse_Index