In all three locations, plans had been changing, right until the last minute. This was the moment of truth for two school classes and their teachers, a handful of Chalmers students, several radio astronomers and two unsuspecting telescopes.
On the stone steps to the playground at the Lövgärdesskolan, a school on the north side of Gothenburg, the entire year 4 gathered to look at the eclipse. They were well prepared. Science teacher Catrine Berglund had sneaked in micro-lessons about space throughout the spring term, and students had painted space motifs on corridor walls to add to the excitement. And the day before, Robert Cumming from Onsala Space Observatory had delivered two "sun cradles" for projecting the sun safely.
The school had also bought in special eclipse glasses for the whole class - useful for anyone who wants to look at the sun. But the clouds looked dishearteningly dense and grey. Would the sun come out at all?
In Slottsskogen Park in central Gothenburg, another group gathered: a handful of students in the newly started network Upprymd. During the spring, they had met over Zoom to be trained in public engagement about space. Now getting to know each other in person for the first time, they could start their mission as communicative astronomers.
Equipped with binoculars and a cardboard screen, the plan was to show the eclipse to other park visitors. Here, clouds and eye protection were part of the challenge. How could they balance keeping a good corona-safe distance, but at the same time being open and friendly?
South of the city, at Onsala Space Observatory, Robert Cumming and Eskil Varenius took the opportunity to try a new way of viewing the solar eclipse with the observatory's smallest radio telescopes, SALSA, as part of a third project, “SALSA for years 7-9”, funded by the Swedish Research Council. With an improved user interface, SALSA is currently being adapted to make radio astronomy projects possible for students in their younger teens.
Here, at least, the weather wasn’t a problem. Radio telescopes can see the sky through thick clouds, and SALSA is no exception. But they had never been used before to see a solar eclipse, and the software was also brand new and untested. On top of that, the plan was to show SALSA live on a link for the school in Gothenburg. Would it really succeed?
And just where had the sun got to? The wait was nervous in all three places. Gaps finally appeared in the clouds, first in Onsala, then over the park, and finally also at the schoolyard, but those moments were few and easy to miss.
There! The round disk of the sun, clearly with a chunk missing! For those who got a look, it really was a moment to remember.
The kids on the school stairs didn’t all see the eclipse, but everyone had experienced something out of the ordinary. A reporter from local radio station was on hand to broadcast live, and young enthusiasts Amina and Huzaifa and their friends got to explain the phenomenon to the listeners. In the city park, the students chose eclipse glasses over projection as the best way to share the sight of the cloud-shrouded eclipse, but everyone was satisfied in the end. In Onsala, the measurements clearly showed that the moon really had blocked some of the sun’s radio waves - the experiment was successful. Network issues affected the live connection to the school (and to some extent also the observatory's high-tech reputation). But contact was made and everyone got to say hi.
After almost two hours, the sun was back to being whole again and it was all over for this time. However, all three projects will continue during the rest of the year. At the school, a special space day is planned for 23 September 2021. For the student network Upprymd, there will be online question and answer sessions with school classes and other events. They’ll also test SALSA and its new software, and start to help school students and teachers make their own radio observations.
For the solar eclipse over western Sweden we’ll have to wait until 25 October 2022. What are we going to come up with for that? With a bit more science capital to spare, there will be new opportunities for everyone.
The project with Lövgärdesskolan is run in collaboration with the City of Gothenburg, the housing company Poseidon and space industry company CAES (Cobham Gaisler).
Text: Robert Cumming
A (top) Johannes Reldin photographed the eclipsed sun through the mesh of one of the SALSA antennas.
B SALSA and Robert Cumming on a live link from Onsala with year 4 students. Photo: Eva Loström/Lövgärdesskolan
C Students in the Upprymd network watching the eclipse in Slottsskogen park. Credit: Andri Spilker
D Radio partial eclipse: the top graph shows measurements with SALSA throughout the day on 10 June 2021. During the solar eclipse (dashed lines mark its beginning and end) the radio waves from the sun were clearly less than usual. (Credit: Eskil Varenius)