Monday , June 21 2021

The Czechs revived the famous film Einstein’s Solar Eclipse

NASA’s Association of Space Research Universities published the photo as a prestigious geoscience film of the day, co-authored by Petr Horálek of the Institute of Physics at the University of Silesia in Opava and Miloslav Druckmüller of the Faculty of Mechanical Engineering at the University of Brno. Technology.

Using modern computational methods of image processing, they tried to reconstruct the image of the solar eclipse on May 29, 1919, which led to the confirmation of Einstein’s general theory of relativity.

“After more than 100 years, people can see for the first time what this phenomenon looked like in colors and what unusual phenomena surrounded the obscured Sun,” Horálek remarked.

Two British expeditions

Einstein began his revolution of thought in 1915 with a series of lectures at the Prussian Academy of Sciences, but he was under unpleasant pressure as his strong pacifism and Jewish origins spurred efforts to discredit him. Fortunately, Einstein’s physical theory fell into the hands of British scientists, who decided to confirm it by experimenting on an expedition to observe a solar eclipse.

Reconstructed image of a total solar eclipse of May 29, 1919

Photo: ESO / Landessternwarte Heidelberg-Königstuhl / FW Dyson, AS Eddington and C. Davidson, P. Horálek / Institute of Physics in Opava, M. Druckmüller / Technical University of Brno

One of the many consequences of general relativity is that the light of a distant source may deviate slightly in its path due to the gravity of another material body. According to the general theory of relativity, the Sun, by its gravitational action, should reflect the light of stars passing in its vicinity, which would be reflected in the photograph of stars with their distance from the Sun. The question was whether theories could be tested in practice.

Scientists from the Royal Observatory tried this: they took advantage of a total solar eclipse on May 29, 1919, when the moon obscured the glittering solar disk and faint stars appeared in the constellation Taurus for a few minutes. According to Horálek, these stars should theoretically be “slightly” different from the obscured Sun, as if our material parent star were not between them and the observer.

What do we see in the picture?
The dark lunar disk obscures the solar disk and reveals a weakly structured solar corona – the flame plasma envelope of the Sun, formed by its magnetic field. It is also possible to recognize the solar magnetic poles (top left, bottom right) and long equatorial coronal rays.
The image is dominated by a pink bulge – a cloud of cooler plasma hovering over the solar surface. Such a giant bulge is very rare during a total solar eclipse and is probably the largest ever photographed during an eclipse.
“As far as the stars are concerned, right next to the Sun we can clearly see below right, one above, one far left … The image is cut from the original panel, so there are fewer stars there,” Horálek explained to Novinky.

“At the beginning of the 20th century, however, there were no digital megapixel cameras, travel agencies and accurate weather forecasts or satellite imagery, so astronomers had to invest a great deal of diplomacy and adjust the expedition so the phenomenon could be well recorded on photographic plates,” he explained. . Choral.

There were two expeditions coordinated by Frank W. Dyson (1868-1939) and Arthur S. Eddington (1882-1944). The end of the First World War was eventually recorded by scientists, and carefully packaged instruments were taken to Liverpool, from where the expeditions traveled with the steamer Anselm to Madeira on Saturday, March 8, 1919.

One of them, led by Andrew CD Crommelin (1865-1939), traveled to Sobral, Brazil. Eddington then led an expedition to Prince’s Island in the Gulf of Guinea. Both had problems with the clouds during the eclipse, but in the end several high-quality shots were taken on photographic plates, which were later successfully imported back to Britain in July and August 1919, despite the complications of the trip.

Eclipse image from 1919 with the highest resolution (with star identification)

Photo: ESO / Landessternwarte Heidelberg-Königstuhl / FW Dyson, AS Eddington and C. Davidson

In the end, the results were excellent and provided scientific visibility to both the members of the expedition and Einstein himself. The stars surrounding the Sun during the eclipse were bright enough to be able to compare with their positions on the plates occupied later when the Sun was not among them. It turns out that their position actually deviates by up to 1.75 arcseconds due to the Sun’s gravity.

The originals are lost, we now have a color picture

Unfortunately, the original records were lost from this eclipse, but fortunately copies of one of them were made and sent to observatories around the world.

One copy of the film from Sobral also arrived at the Heidelberg-Königstuhl observatory in Germany, which recently digitized it. In cooperation with the intergovernmental organization European Southern Observatory (ESO), Horálek obtained a digitized copy of the original record in the highest possible quality.

“At first glance, it was clear that the image quality was far from instantaneous, and the scan was scratched and full of dust particles. It is also quite clear that at the time of the eclipse, the clouds were really obstructed by Sobral,” he described.

According to him, the digital shape of the glass panel had to be adapted so that some artifacts disappeared, while the real structures of the solar corona stood out. The result was then processed by Professor Druckmüller’s NAFE program from BUT. And finally, we also managed to reconstruct the color of the whole image, which was previously only available in black and white.

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