Every student knows that Mercury is the planet closest to the Sun in our solar system. Nevertheless, for several decades in the 19th century, many of the world's leading scientists had good reason to believe that the planet, dubbed Vulcan, was somewhere within the orbit of Mercury. The famous French mathematician first suggested the existence of this phantom planet in 1859, and it remained one of the most wanted celestial objects until Albert Einstein's theory of relativity finally debunked the mystery in 1915.
The mystery of the orbit of Mercury
In 1859, French scientist Urbain-Jean-Joseph Le Verrier began working on one of the most mysterious problems in astronomy: the orbit of Mercury. For years, astronomers have noted that this small planet in the solar system appears to be following its own course as it orbits the sun. In particular, its perihelion - the point where the planet is closest to the Sun - shifts slightly in each orbit. According to Sir Isaac Newton's law of gravity, this discrepancy can easily be explained by the presence of other celestial objects. Yet even after Le Verrier calculated the gravitational pulls of Venus, Earth, Mars, and Jupiter, his predictions of Mercury's orbit were always slightly inaccurate. The planet never ended up where it should have been.
Le Verrier hypothesis
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After carefully checking and re-doing his calculations, Le Verrier proposed an innovative hypothesis: some other object, unknown and invisible, is exerting gravitational attraction into the orbit of Mercury. This planet, or a group of small planets orbiting in the immediate vicinity of the orbit of Mercury, is capable of performing an anomalous effect, which is felt by the last planet. Le Verrier suggested that the glare of the sun prevented the identification of this object in the past. However, he argued that it could be easily detected under the right conditions.
Dear Astronomer
The scientific community welcomed Le Verrier's theory, and for good reason, since he already had experience in finding new planets. Thirteen years earlier, he had made a similar prediction while trying to explain the gravitational fluctuations in the orbit of the planet Uranus. When astronomers scanned the sky, they discovered the previously unknown planet Neptune. The discovery provided Le Verrier with international scientific fame and secured admission to the French Order of the Legion of Honor and the post of head of the Paris Observatory. His intelligence has been described as "almost superhuman."
"Discovery" of a new planet
Armed with a fresh prediction from the discoverer of Neptune, astronomers immediately began their hunt for a new planet. But it turned out that the breakthrough happened a few months earlier, and was made by an amateur named Edmond Modest Lecarboll. A physician by profession, Lecarbolle was also a keen astrologer who built his own makeshift observatory in the countryside. Looking through his telescope on March 26, 1859, he saw a small black dot - possibly a planet - drifting across the sun's surface. At that time, the doctor did not tell anyone about his discovery, but after reading notes on the hypothetical planet Le Verrier, he sent him a letter with a full report.
After receiving the letter, Le Verrier went to meet with Medicol to examine his equipment and notes. After this meeting, he was even more convinced that there is another planet closer to the Sun than Mercury. Le Verrier announced the opening in early 1860. Obeying the tradition of calling the planets by the names of mythical gods, he gave her the name Vulcan, in honor of the Roman god of blacksmithing.
Unsuccessful observation attempts
The discovery of Volcano was a big step forward for science. Medicol was admitted to the Legion of Honor, and Le Verrier was once again called a genius. There was only one problem: the new planet was frustratingly hard to find. Scattered information about the observation of the Volcano poured in from around the globe, but most of it was from amateur astronomers. Le Verrier still required independent confirmation from a respected professional. In the hope of getting this confirmation, Le Verrier's supporters calculated that the planet could be seen in late March - early April 1860. Astronomers set up their telescopes, but when the appointed time came, Vulcan never showed up. Many soon began to wonder if this planet actually existed.
Volcano hunting
Over the next few years, the Volcano became the subject of international hunting. During the 1860s, there were many observations, but for every astronomer who claimed to have seen the planet, there were so many who tried and never found anything. The ranks of skeptics continued to grow until 1871, when a team of English astronomers failed to locate the planet for the third consecutive year. The question of the Vulcan remained open since 1859, as the author Thomas Levenson wrote in his book "The Hunt for the Volcano". Random observations and seemingly consistent calculations fueled this interest.
In 1876, Vulcan's fate seemed to be sealed. A qualified astronomer reported that he was observing the transit of a planet near the Sun, and the newspapers received another flurry of messages from amateurs. The enthusiasm was so high that an article appeared in The New York Times claiming that "the existence of Vulcan can no longer be denied or ignored." According to the article, the Earth should henceforth be called the fourth planet from the Sun, and children in public schools who study the old-fashioned order of the planets should definitely remember Vulcan and its place in the solar system.
Fall from Olympus
Le Verrier died in 1877, but the most eventful period in the life of Vulcan was still ahead. Only a year later, on July 29, 1878, there was a total solar eclipse that could be observed in Russia and North America. An event like this was very convenient for observing Vulcan, and therefore legions of astronomers set up their telescopes and cameras in the hope of seeing it. Most surrendered quickly enough, but two respected astronomers - James Craig Watson and Lewis Swift - claimed to have spotted the planet. Newspapers began to trumpet the existence of Vulcan again, but this triumph was short-lived. Critics said that scientists actually saw two well-known stars, and most of the scientific community dismissed these observations as erroneous.
After the observations of Watson and Swift were criticized, the scientific community's faith in Vulcan practically disappeared. This planet became the equivalent of the myth of El Dorado in astronomy, abandoned by most scientists, although some still continued to search for it. However, if Vulcan does not exist, scientists again began to wonder what is causing the displacement of Mercury's orbit.
Solving issues
The final answer to this question finally came in 1915 when Einstein threw a scientific bomb, which became his general theory of relativity. Unlike Newton's theories of gravity, which could only explain Mercury's orbit by the existence of an unknown planet, general relativity states that a supermassive object - in this case the Sun - is capable of bending space and time and changing the path of light. Shortly before his theory was published, Einstein applied it to Mercury and found that it perfectly explains the inconsistency of its orbit. Thus, Mercury is not attracted by any object, and we are talking about moving through a distorted time space.
As a result of Einstein's breakthrough, Volcano was forever thrown from the astronomical sky. Astronomers erased the planet from their charts, and the news of past observations was attributed to the appearance of unidentified stars or sunspots. The volcano at the same time became one of the most famous dead ends in scientific history, but its "death" did not put an end to the hunt for new worlds within the solar system. In 1930, after a long search, the dwarf planet Pluto was discovered. In the meantime, in recent years, scientists have found enough evidence that a hypothetical "ninth planet" may be located somewhere on the outer edge of the solar system.
Anna Pismenna