Vulcan was first named in 1860, but in 1846, astronomer and mathematician Urbain Le Verrier sat down and tried to locate the planet humans had never seen before. Although its existence was doubted, everything indicated it was there. And that ‘everything’ was the calculations of eminent scientists who knew to perfection the Universe that Isaac Newton had bequeathed and the laws that governed it since 1687.
The law of universal gravitation had explained the celestial motion of the stars without a doubt for two centuries and, according to that theoretical framework, the only thing that could explain the orbit of Mercury, one of the most puzzling phenomena of the Solar System, was the existence of a planet that had not been sighted until then.
Identifying a New Planet, Vulcan
Although the discrepancies were small, there was a difference between the observed orbit of Uranus. Le Verrier proposed that the difference could be explained by another planet beyond Uranus and made predictions about the orbit of this previously unknown body.
During the 17th and 18th centuries, new moons around Jupiter and Saturn, numerous galaxies and nebulae, and even a new planet Uranus, were discovered. In the middle of these centuries, irregularities were observed in the orbit of Uranus that could only be explained by the presence of a new planet similar in size to Uranus itself, but located beyond it.
A few years later, Neptune was discovered thanks to mathematical predictions. This was seen as a resounding success of Newton’s universal gravitation. Neptune was discovered in 1846, thanks to the predictions of Urbain Le Verrier. So, it is not surprising that when observing irregularities in the orbit of Mercury, in 1859, he proposed the existence of a new planet between the latter and the Sun.
To solve the unknown, Le Verrier followed the same method, with the same meticulous attention to detail, after calculating the influence of the gravitational pull of Venus, Earth, Mars, and Jupiter, his predictions of Mercury’s orbit were always slightly wrong. Mercury was simply never where it was supposed to be, according to all the knowledge of the time.
The solution to the riddle had to be, as in the case of Uranus, the presence of Vulcan, although he was not sure. Months later, an amateur astronomy doctor named Edmond Modeste Lescarbault had observed with his telescope a black dot passing in front of the Sun, had taken note of the size, speed, and duration of the transit, and after reading about Le Verrier’s hypothetical planet, sent him a letter with all the details.
The renowned astronomer went to visit him, reviewed the doctor’s equipment and notes, and excitedly announced the discovery of Vulcan in early 1860.
Vulcan Is Expelled
The real or imaginary existence of Vulcan came to an end at the Prussian Academy of Sciences when Albert Einstein disrupted the vision of the Universe with his Theory of General Relativity when he discovered the anomalies in the orbit of Mercury. As a result, it seems that these anomalies were not due to the presence of an unknown planet, but to the fact that Newton’s Gravitation was not entirely accurate.
Once the corrections given by Einstein’s new theory were introduced, the problem was solved, and the advance of Mercury’s perihelion was explained. As such, Einstein’s theory could explain both the orbit of Mercury and the orbit of the Earth, Mars, Jupiter, etc. without resorting to additional planets, therefore, the planet Vulcan no longer existed.
What does Einstein’s theory say? General Relativity says that space and time are not static, but dynamic and can change, and what Einstein argued to explain the peculiarity of Mercury’s orbit was that a massive object, in this case, the Sun, was able to bend space and time and alter the path of light so that a ray passing near the Sun travels a curved path.
This story was written in Spanish by Perla Vallejo in Cultura Colectiva News
