Three Times That Solar Eclipses Transformed Science

This article is part of a special report On the total solar eclipse which will be visible in certain parts of the United States, Mexico and Canada on April 8, 2024.

Total solar eclipses, such as that which takes place through a strip of North America in April, are among the most sublime and transcendental natural phenomena that can be experienced. The spectacle of the whole – when the moon completely covers the sun to launch a dark shadow on earth below – is almost unreal, as if the natural rhythm and the regular order of the cosmos were defeated. It is therefore not surprising that throughout history, these events prompted fear, wonder and reverence. They were also an ideal opportunity for astronomers to test advanced theories of physics and to discover new aspects of our natural world. Here are only three of the many times that a total solar eclipse has transformed our views of the heavens, the earth and everything else.

Halley’s eclipse

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If it was not for Edmond Halley, we may never have had Isaac Newton’s revolutionary theory of gravity. In 1684, one of the contemporaries of Halley, Robert Hooke, claims to be able to derive the laws of Kepler on the planetary movement from simpler principles. However, when he was challenged, however, he could not save him. Halley had also agreed to take a crack in the problem, only to be short, so he turned to his old friend Newton. Newton surprised Hooke saying he had already found a solution but had “lost” the notes. To satisfy Halley’s persistent encouragement, Newton may have produced the greatest work of physical insight, his Principia Mathematica.

To say that Halley was the Newton’s surface would be an understatement. Halley personally financed the first publication of Newton’s work and played a key role in communication of its importance and importance to the public. In doing so, he became the first known first person in history that predicted with precision a next solar eclipse.

Cultures throughout history had succeeded in supposing approximate assumptions at the time of eclipses. However, by exercising freshly struck gravitational laws from Newton, Halley was able to predict the calendar and the path of a total solar eclipse which passed in London on May 3, 1715 with decent precision. The timing and the path were correct at about four minutes and 20 miles, respectively. (Halley may have been rejected not from the failure of Newton’s laws but due to inaccuracies in the archives of the Moon Movement).

Naturally, the event made the headlines of journalists and laity around the world recognizing Newton’s genius. And the way in which Halley has chosen to map the geographical path of the eclipse (with dark bands showing all and partiality) was so good that we always use this style today.

Janssen’s eclipse

In the mid-1800s, chemists, physicists and astronomers were broken above the new spectroscopy technique, in which to divide the light in arc-diable spectrum of its constitutive colors could reveal the elementary composition of a source. (Exactly what these elements were was always ready to debate because the atoms had not yet been proven to exist!))

Using spectroscopy, astronomers could, for the first time, look through their telescopes and identify the substance of what they saw as easily as if they could reach out and touch these distant planets and stars. Today, spectroscopy is the foundation of modern astronomy. For each attractive astronomical image of a celestial object that you can meet, there are probably a dozen articles published on its spectrum.

Since the sun is the brightest thing in the sky, it was a natural target for spectroscopy. With this technique, astronomers have found hydrogen, iron, oxygen, carbon and more hidden in the incandescent atmosphere of the sun – as well as indications of an element that has challenged easy understanding. The first observations suggested that this could be a strange type of iron, but no explanation fully corresponded to the data.

A critical advance occurred on August 18, 1868, when international astronomers observed a total solar eclipse in southern India and Southeast Asia. Among them were Norman Lockyer and Jules Janssen, who studied the spectra of solar protomes together which were suddenly visible around the blackout silhouette of the moon. These specters allowed them to dispel the darkness, clearly revealing the presence of a new element on the sun which was previously unknown on earth.

It would take decades to the chemists linked to the earth to isolate the element, which they named the helium, after the Greek word heliosmeaning “sun”. Helium was the first – and to date only – elements discovered in the heavens before being found on earth.

Eddington’s eclipse

As beautiful and precise as the story of Newton’s gravity, it was incomplete and could not adequately explain certain phenomena, such as the precession of the orbit of mercury around the sun. Such incompleteness was a key factor for the efforts of Albert Einstein to forge a new concept of gravity – his general theory of relativity, which deals with gravity as the curvature of space -time induced by massive objects. With general relativity, Einstein was able to explain the mysteries of Mercury’s orbit. It was technically a postbone, However, the concoction of a theory to explain the results already known. What he needed was a prediction– Something new to demonstrate how powerful his theory was.

Einstein quickly struck the idea of ​​using general relativity to predict the extent to which light must be deflected by the gravitational field-that is to say the curvature of space-time-a massive object like the sun. The gravity of the sun should slightly deviate from all the passing light rays. Normally, we cannot see this effect, because it is incredibly tiny, and most of the light rays of the distant stars do not pass sufficiently close to the sun. But during a total solar eclipse, someone could potentially measure the precise position of a star directly on the apparent edge of the sun, then compare their position at any other time to discern this deviation.

Newton’s theory also predicted this type of deviation, and the first incursions derived from Einstein relativity found identical results. In an article in 1911, Einstein urged astronomers to seek this effect. Although they tried several subsequent eclipses, their attempts were spoiled due to bad weather.

It turned out to be a good thing for Einstein: once he has fully expanded his theory, he realized that his calculations have given a stronger deviation than planned by Newtonian gravity. After Einstein has once again asked for the help of his astronomical colleagues, Frank Watson Dyson and Arthur Eddington, took up his challenge. Direct two expeditions – The island of the island in principle and the other in Brazil – these astronomers measured the apparent positions of the stars near the sun during the total solar eclipse of May 29, 1919 and discovered them alignment according to exact function with the predictions of Einstein.

The following year, during a dinner at the Royal Astronomical Society, Eddington recited the following poem, which he had written as a parody of THERubáiyát d’Omar Khayyám.

Oh leave the wise men our measures to bring together

At least one thing is certain, the light has weight

One thing is certain and the rest debate

The light rays, near the sun, are not straight.

The eclipse of tomorrow

Nowadays, earth -related astronomers generally do not need to wait for the next fateful alignment of the moon to study the sun because they can make their own “eclipse” on demand with an intelligent instrument called coronagraph. These devices can be as simple as a disc affixed to a telescope that precisely blocks the sun. Astronomers often use coronagraphs to study the external atmosphere of the sun, where there are still a lot of mysteries to find: no one knows yet Exactly Why this region is so burning, compared to the visual surface of the sun, why it has such strong and tangled magnetic fields or why it is capable of launching the endless flow of loaded particles called solar wind.

The natural eclipses of the past have helped us to revolutionize our perspectives of the universe, and those of human presentation will surely propel us into the future of astronomy. Who knows what new secrets will the sun reveal to us then?