Wednesday , June 16 2021

Czechs portray Einstein’s famous solar eclipse movie

The NASA Space Research Universities Association has published a photo as a prestigious geoscientific film of the day, co-author of Petr Horálek of the Institute of Physics of the Silesian University in Opava and Miloslav Druckmüller of the Faculty of Mechanical Engineering at Brno University. Technology.

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

“After more than 100 years, people can see for the first time what this phenomenon looks like in colors and unusual phenomena surrounding the hidden Sun,” Horálek said.

Two British expeditions

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

Reconstructed image of a total solar eclipse from 29 May 1919

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

One of the many consequences of general relativity is that the light from a distant source deviates slightly from its path due to the gravity of another material body. According to the general theory of relativity, the Sun, with its gravitational effect, must deflect the light of the passing stars; this light will be reflected in the photograph of the stars away from the Sun. The question was whether the theories could be verified in practice.

Scientists from the Royal Observatory tried to do this: on May 29, 1919, when a dazzling solar disk was darkened by the moon and faint stars appeared for several minutes in the constellation Taurus, they took advantage of a total solar eclipse. According to Horálek, these stars should theoretically differ “slightly” from the indeterminate Sun, since our material parent star was not between them and the observer.

What do we see in the picture?
The dark moon disk conceals the solar disk, revealing a pale solar corona – an expanded plasma envelope shaped by the Sun’s magnetic field. It is also possible to recognize the solar magnetic poles (upper left, lower right) and long equatorial coronal rays.
The image is dominated by a pinkish protrusion – a cooler plasma cloud orbiting the surface of the sun. Such a massive protrusion is very rare during a total solar eclipse and is probably the largest protrusion photographed during an eclipse.
“As for the stars, we can clearly see two right next to the Sun, one at the bottom right and one at the far left … The image is a cut from the original plate, so there are fewer stars there,” Horálek explained for Novinky.

“But at the beginning of the 20th century there were no digital megapixel cameras, travel agencies, and accurate weather forecasts or satellite images, so astronomers had to spend a great deal of diplomacy and adapt the expedition to record this phenomenon well enough on photo plates,” Horálek explained.

Two expeditions were organized, coordinated by Frank W. Dyson (1868-1939) and Arthur S. Eddington (1882-1944). It was the end of the First World War, finally recorded by scientists, and carefully packaged instruments were taken to Liverpool; The two expeditions went to Madeira together on the Anselm steamboat on Saturday 8 March 1919.

One of them, led by Andrew CD Crommelin (1865-1939), traveled to Sobral, Brazil. Eddington then embarked on an expedition to Prince Island in Guinea Bay. Both had problems with clouds during the eclipse, but eventually sufficiently high-quality recordings were made on photo plates, and these were later successfully brought back to England in July and August 1919, despite travel difficulties.

Highest resolution 1919 eclipse image (with star identification)

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

In the end, the results were excellent and earned scientific recognition for both members of the expedition and Einstein himself. The stars surrounding the Sun during the eclipse were bright enough to be compared later with their positions on the plates taken when the Sun was not between them. It turns out that their position actually deviates by up to 1.75 arc seconds due to the Sun’s gravity.

Originals disappeared, now we have a color picture

Unfortunately, the original recordings were lost from this eclipse, but thankfully copies of one of them were made and distributed to observatories around the world.

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

“At first glance, it was clear that the image quality was far from the current level and the scan was scratched and full of dust particles. It is also quite clear that the clouds were really blocked by Sobral during the eclipse,” he explained.

According to him, it was necessary to adjust the digital shape of the glass plate so that some artifacts disappear and, on the contrary, the real structures of the solar corona stand out. The result was later processed by Professor Druckmüller’s NAFE program from BUT. And finally, we were able to reproduce the color of the entire image that was previously only available in black and white.

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