A Total Solar Eclipse in Brazil proved Einstein's Theory more than 100 years ago
A total solar eclipse observed in 1919 by scientists in the state of Ceará, Brazil, proved Einstein's Theory of General Relativity. Understand more here.
Last Monday (8), a total eclipse of the Sun occurred, which can be seen in some places in the United States, Mexico and Canada. The news and images flooded social networks...
Because now we are going to talk about another astronomical event of this type that was very important for science: a total solar eclipse occurred in 1919 in the city of Sobral, located in the interior of the state of Ceará, in Brazil. And what is important about this? It was thanks to him that the Theory of General Relativity of Albert Einstein (1879-1955), the famous German physicist, could be proven by Brazilian and English scientists at the beginning of the last century.
How did the 1919 solar eclipse validate Einstein's Theory?
In 1915, Einstein announced his Theory of General Relativity, which states that the mass of bodies deforms the space near them, causing the path of light, when passing through the deformed space, to cease to be a straight line because of the deviation.
That is, Einstein discovered that the presence of matter causes space-time to bend around the object, be it a star, a planet, etc.; and the greater the mass of the object, the greater the curvature.
With this, his theory could only be proven (or not) when there was a total solar eclipse, in which it would be possible to observe the stars behind the Sun and if the brightness emitted by them would suffer a deviation when passing through the space deformed by the Sun. Thus, the next solar eclipse that would occur at that time for such proof was precisely that of 1919.
The city of Sobral was one of those chosen for the observation of scientists, since it was right in the middle of the path of the totality (trajectory in which the shadow caused by the Moon in front of the Sun would be total). The other city chosen was Île do Príncipe, in the archipelago of São Tomé and Príncipe, in Africa.
According to the Theory of General Relativity, large masses change the curvature of space, producing gravity. When light propagates in regions of space highly distorted by large masses, its path is curved.
In Sobral, the weather conditions were good, and just before 9 a.m., on 29 May, 1919, the population watched the total solar eclipse, which lasted about five minutes. There, scientists were able to register 12 different stars. On Île do Príncipe, the weather was bad and hindered the observation of the phenomenon.
The record of these stars was then used as a reference to measure the angle of deviation of the trajectory of their light beams. A few months later, the scientists presented the results of the observation. The records made during such an eclipse proved Einstein's General Theory of Relativity, announced years earlier, which made him famous worldwide.
But what is a total eclipse of the Sun?
A total solar eclipse occurs when the Moon is positioned between the Earth and the Sun, totally blocking sunlight, and only the crown of the Sun is visible.
The next event of this type will take place again on 12 August, 2026, but will not be visible in Brazil. Its entire route will pass through northern Spain, through Portugal, Iceland, Greenland and Russia. In Brazil, the next one we can see will only take place in the year 2045.