The Paris Observatory was built and financed by King Louis XIV from 1667 to 1672 (Shutterstock)

On a rainy day in May 1673, deep in the dense forests of French Guiana (a French overseas department), a scientist died. He was known to historians only by his first name, Maurice, and he may have suffered a fatal illness or accident, but the full description of his death was not accurately recorded, and the only person with him was his partner, the French astronomer Jean Richer, who fell ill and was fighting for his life.

The duo was sent to Cayenne, the capital of Guyana on the northeastern coast of South America, in 1672 from Paris, 4,400 miles away. They were sent by the French Academy of Sciences (which was founded in 1666 during the reign of Louis It would reveal the distance between the Earth and the Sun, a value not yet known.

In this report, we follow the scenes of this risky journey, what the two French scientists Richer and Morris discovered, the risks they were exposed to, how they ended up with Morris’s death and Richer’s miraculously surviving, and how did their findings contribute to understanding the solar system?

Endeavors to reach the sun

Before delving into the depths of the journey, it must be pointed out that what the two French scientists achieved was only one step in a long path to understanding our solar system. Man has always stared at the sky, and there have been attempts to determine the distance to the sun, and scientists in ancient times produced estimates that differed. Significantly, and often greatly underestimate the true value.

The first of these estimates was made by the Greek astronomer Eratosthenes. He was the first to calculate the tilt of the Earth's axis in the third century BC. He was one of the first accurate observers of celestial phenomena. He was able to calculate the size of our world with a very high level of accuracy. After a long journey, he was able to calculate the size of our world with a very high level of accuracy. From deducing the distance between the Earth and the Sun, but with less accuracy, he estimated it to be 20 times the distance between the Earth and the Moon, or about 7.4 million kilometers.

With the passage of more than 1,500 years and the emergence of brilliant astronomers such as the founder of modern astronomy, Nicolaus Copernicus, the first to formulate the heliocentric theory, and Tycho Brahe, who played an important role in the advancement of astronomy before the advent of the telescope, neither of them was able to modify the distance that Eratosthenes estimated (equal to half The diameter of the Earth is approximately 1142 and 1150 times) or devise a similar method.

Illustration of scholars at the Library of Alexandria (social networking sites)

With the transition of astronomy from Greek civilization to Islamic civilization, astronomers made some modifications to the cosmological model of Eratosthenes, but they did not significantly change the time and distance to the sun that Eratosthenes estimated. For example, the Arab astronomer and mathematician Ahmed bin Katheer Al-Farghani explained in his introduction to epicycle astronomy in the Ptolemaic system that the solar distance is equal to half the diameter of the Earth by about 1170 times, while Muhammad bin Jabir bin Sinan Al-Battani, nicknamed “Ptolemy of the Arabs”, used the distance in his astronomical tables. The sun is equal to the radius of the Earth by about 1108 times, and later astronomers, such as Abu Al-Rayhan Al-Biruni, author of the book “The Key to Astronomy,” used values ​​similar to these distances.

Eratosthenes's calculations of the distance between the Earth and the Sun survived until the 16th century. With the invention of the telescope in 1635, the Belgian astronomer Godefroy Findelin was able to conduct more accurate studies that the naked eye could not determine. He found that Eratosthenes’s distance from the Sun was about 11 times less than the real distance, and estimated it at 81 million kilometers.

In the late seventeenth century, new European scientific institutions attempted to take advantage of trade networks to achieve their own goals, but achieving this goal proved extremely difficult.

According to Nicolas Dieu in his book Science and Empire in the Atlantic World, the early expeditions of the French Academy of Sciences are usually seen as inaugurating a new era of precise measurement in astronomy, geodesy and cartography, but it was the voyage to Cayenne that brought The fundamental data that, combined with Cassini's mathematical prowess, produced the first precise measurement of the vast distance between the Earth and the Sun.

Years before the trip

On January 11, 1667, five years before the launch of the expedition to French Guiana, the French astronomer Adrien Ozot stood in the meeting room of the King's opulent library in Paris, and before a small gathering of men wearing long, thick wigs, he laid out a bold program. For scientific research.

Ozot's program was broad, with a vision of using colonial trade to send observers to points around the world to make observations in astronomy, and he realized that some astronomical questions—including the distances to the planets and the Sun—required simultaneous observations in two different locations, as The situation is in Paris and in a remote area.

According to Paris-based researcher Dinaba Young in an article in National Geographic magazine, Ozot called for astronomical expeditions to Madagascar in East Africa, where the French East India Company, founded in 1664, was expected to begin operations. Leveling will allow astronomers to obtain basic observations.

As the men listened, the sounds and smells of the busy city might have wafted through the windows. In the late 17th century, Paris was known for its rowdy church processions, drunken parties, and gun violence. At 7 a.m. every day, city officials would walk the wide streets, ringing large bells to wake residents, directing them to clean up the dirt that had accumulated in front of their homes or risk paying a fine.

The bustling city was a hotbed of intellectual activity and commerce, with a large wealthy population mingling with members of the scientific community. Many of the most skilled makers of scientific instruments were based in Paris at the time, and on the outskirts of the city construction began on a large new astronomical observatory.

Two years after Ozot's speech, in April 1669, Cassini arrived in Paris with a cart full of astronomical instruments after being personally invited by the most powerful king in Europe, Louis XIV of France, and quickly became one of the leading figures in the academy.

Cassini's abilities attracted the attention of Louis

Painting showing King Louis XIV at the opening of the Paris Observatory in 1667 (Shutterstock)

By the 1670s, with the help of newly developed astronomical instruments, Cassini devised a series of ambitious research programs, and was determined to find the answer to the question, “How far is the Sun from the Earth?” Gabriella Bernardi describes in her book, “Giovanni Domenico Cassini...A Scientist Modern Astronomy in the Seventeenth Century”: “He had no hobbies, and from his memoirs a man completely devoted to his profession appears.”

From Madagascar to Cayenne

As the academy continues to prepare for an astronomical mission to the equator, scientists have shifted their focus from Madagascar in East Africa to Cayenne on the northern coast of South America. This French settlement was a shorter distance away, and the Academy had to act quickly to catch a noteworthy event; This is because in the fall of 1672, Mars and Earth will be at their closest point to each other in 15 years.

By observing Mars at the same time from two different locations on Earth, scientists were able to calculate the apparent difference in Mars' position compared to the background stars, known as parallax.

The trip to French Guiana at the time was routine, part of a series of scientific missions sent by Cassini. Reacher and Morris had previously traveled to northeastern North America two years earlier to measure latitudes and tidal heights, and French scientific missions followed them to destinations such as Senegal and Ecuador. .

Cassini had set Reacher several goals: to measure the positions of the southern stars, tidal heights, and the duration of twilights, observe Jupiter's moons, and take detailed notes on the movements of Venus, Mars, and Mercury. He and Morris were also expected to make barometric measurements and observe unusual plants and animals.

A dangerous journey

Richer and Morris spent several days and nights working alongside Cassini to prepare for the joint observations they would have to conduct thousands of miles away, and as the days passed the duo knew they were embarking on a dangerous journey.

Richer and Maurice traveled first to the French port of La Rochelle, and spent 3 months testing their instruments, including measuring instruments, several telescopes of different sizes, and a few pendulum clocks.

On February 8, 1672, they sailed to Cayenne on a merchant ship that was probably an empty slave ship en route to Senegal, and less than two months later they arrived at their destination on April 22, 1672.

The small, desolate settlement was not an encouraging sight for Richer and Morris. Cayenne, visited by only two or three ships a year, was separated from the rest of Guyana by the mouth of the narrow 11-mile-long Mahury River on one side and the narrow Cayenne River on the other.

When they got off the boat, they both probably realized that they had chosen the wrong time to embark on this trip. In the Amazon region, late April is the peak of the monsoon season and heavy rains flood the river. The weather is very humid and mosquitoes abound.

In the center of the settlement was the wooden fort of Siperu, named after the indigenous leader, a bleak and isolated building that had been rebuilt in stone after the final attack by the indigenous people, demonstrating the determination of the French colonists to survive. A short walk from the fort was a general store that served the settlement and often had little on the shelves, and there was also a modest church and mission house.

Catherine Lussier described Cayenne in 1685 in Caen's Supplies in the Ancien Regime... Archeology and History of Trade Networks; It was a dwelling occupied by four fathers and a brother, along with 82 enslaved Africans (32 men, 23 women, and 27 children) to work the Jesuits' crops and care for their livestock. Enslaved Africans made up about 85% of the settlement.

On this land there were the Kalina people, also known as the Caribs, the indigenous peoples of the northern coastal regions of South America. The indigenous people - also called the “Galipe” - had resided in the Cayenne region for more than two thousand years before the arrival of the Europeans, and the interactions were The precedent between the two groups is uneasy. As one settler, Paul Boyer, wrote after a visit around 1654: “All the Gallibies could think of was how to get rid of the French.”

On May 14, Jean Richter calculated the height of the North Star, which is a star above the North Pole of the Earth and located close to the Earth’s axis of rotation around itself, so it always appears and is always located in the north (communication sites)

Over the following years, the French temporarily lost the fort to other colonial powers. The Dutch were able to seize control of the colony after a decade of rule by French officer Charles Ponce de Bertigny, but new French forces forced them out in a surprise attack. The British expelled the French settlers in 1667. They regained control of the colony a year later, just four years before Reacher's arrival.

For King Louis Within Guyana, whoever controlled Cayenne would have a direct path to riches, yet Reacher and Maurice embarked on a scientific treasure hunt.

In the face of harsh nature

Far from the disputed settlement, across the narrow river, lies the rest of Guyana, a dense primeval rainforest containing plants and animals found nowhere else in the world. This was an environment rich in anteaters, iguanas, spider monkeys, spotted leopards and bright green parrots; Strange to Richer and Morris, and quite different from the cobblestone streets of Paris.

Academy records indicate that Ritcher and Morris took detailed notes on plants and animals, and at one point Ritcher came face to face with an electric snake, later writing that “a simple touch with a finger or the tip of a stick numbs the arm so that one remains for about 15 minutes unable to move.” However, most of these notes were almost lost over time.

Immediately upon his arrival, Reacher began exploring the forest, looking for the best place to build an observatory. After a few weeks, the two men located a site, recruited indigenous workers and built a structure composed of branches, tree bark and palm leaves, with a large hole in the roof for their telescopes, and by mid-May they had finished the observatory.

Richer's first observation was on May 14 when he calculated the height of the North Star, which is a star above the North Pole of the Earth, and is located close to the Earth's axis of rotation around itself, so it always appears and is always located in the north.

It was a promising start to what would later be a very difficult mission, and Reacher wrote to Cassini telling him that he was unable to record observations for several days at a time due to bad weather conditions. Hardly a day had passed without rain since their arrival, and at one point a large number of ants crawled onto the instruments. This disrupted the delicate machines and caused at least one to stop completely.

Richer and Morris relied heavily on supplies from France, despite the availability of local food in the form of wild game meat, fish, and edible plants such as bananas, avocados, and mangos. The French preferred to eat familiar foods including packages of meat, flour, Bordeaux wine, coffee, and cheese, supplies that were rarely replenished by passing ships, as sending food to the colonies was a constant problem due to the slow mail and the infrequent passage of ships.

Mission accomplished

Finally, in October 1672, the rainy season stopped just in time to observe Mars, and Ritcher measured and observed nearby planets and stars over the course of several weeks.

Across the Atlantic Ocean, 4,400 miles away, Cassini and Danish astronomer Ole Römer also made measurements at agreed-upon times by looking out the window of the Paris Observatory.

Guyana is about 4,400 miles away from Paris (social networking sites)

Meanwhile in London, astronomer John Flamsteed of the Royal London Society for the Improvement of Natural Knowledge (known as the Royal Society) was also measuring Mars's parallax to determine its distance to the Sun, observing Mars once in the early evening, and waiting several hours for it to orbit. He then measures the Earth again, and his final calculations are close, but not quite as accurate as Cassini's.

Comparison of Ritcher's observations of Mars with those made elsewhere made it possible to determine the distances of Mars and the Sun from Earth, leading to the first reasonably accurate calculation of the dimensions of the Solar System and showing that the system was much larger than previously thought.

In the spring of 1673, Maurice died, perhaps of yellow fever, malaria, pneumonia, or even severe malnutrition. Richer, now alone, felt so ill that he could not continue his journey. He searched for samples to bring back to the academy, and caught a live crocodile. He tied him with chains in the hold of the ship.

Falling ill, he boarded ship with a draft of his mission report, and left Cayenne at the height of the monsoon season, with the river about to flood, and rain pouring relentlessly on the land he was leaving behind on May 25, 1673. On the long journey home The crocodile died of starvation, but Reacher recovered.

The ingenuity of astronomer Giovanni Cassini produced the first accurate measurement of the vast distance between the Earth and the Sun (Encyclopedia of Science)

In 1679, the official report of the Ritcher mission was issued, entitled “Astronomical and Physical Observations on the Island of Cayenne.” With the help of the data obtained by Ritcher, Cassini was finally able to make his calculations, declaring in a publication issued in 1684 that “Our Sun, which seemed so close, was in fact at a distance.” 140 million kilometers (87 million miles),” an estimated distance that is remarkably close to the actual distance of about 149.6 million kilometers (93 million miles), a result that took hundreds if not thousands of years to reach.

News of the mission and the revelation of the enormous size of the solar system spread quickly, thanks in large part to the popular writings of Bernard Le Bouvier de Fontenelle, who wrote about science in a unique narrative style and was famous for his simplified treatment of scientific topics. For the first time, astronomy became a popular topic. On dining tables.

Other results

Early modern researchers and statesmen were keenly aware of the need to improve standards of measurement, albeit for different reasons, and the diversity of man-made units across regions and dates was by the 17th century already common and questionable.

The late seventeenth century witnessed many scientists presenting different nominations for a global standard, and the most promising of these projects was the use of the second pendulum as a standard for length, a project that was pursued by the French Academy of Sciences in the 1770s and 1780s, and remained a goal cherished by scientists throughout the eighteenth century. .

Therefore, determining the distance from the Earth to the Sun was not the only legacy left by Richer's expedition to Cayenne. While in South America, he also measured the length of the pendulum and compared the results with his carefully calibrated clocks.

Reacher's observations also led to the discovery of the shape of the Earth. Through the experiment, Richter discovered that the swinging rhythm of the pendulum is a second slower in Cayenne than in Paris, which is located at a different latitude, meaning that gravity must be weaker in Cayenne than in Paris.

Although Richer did not realize this result at the time, it was due to the fact that gravity is slightly lower near the equator, and the Earth bulges out as it rotates in what is known as “equatorial bulge,” which is the bulge of the planet around its equator, causing a measurement The pendulum is a second shorter.

About 15 years later, Isaac Newton discovered the reason, using Reacher's measurements as evidence for his new theories about gravity. The Dutch mathematician Christian Huygens also used this discovery to prove that the Earth is not spherical but is in fact flat at the poles (an oblate spherical body), and therefore Cayenne was farther from Earth. Paris from the center of the Earth.

In 1740, Voltaire wrote in a letter to his friend, the royal advisor and English political writer Lord John Hervey, “Just think, John, that without the voyages and experiments undertaken by those whom Louis XIV sent to Caen in 1672, Newton would not have made his discoveries concerning gravity.” .

Just as the merchant ship that carried him home disappeared from the green shores of Guyana, Reacher also disappeared from sight, and the precise calculation of the distance between the Earth and the Sun became an almost complete victory for Cassini, who believes that the success of the journey was due to the modern approach he took from the regular observing plan, in cooperation With many other colleagues. Once Richer returned safely to France, he separated from the academy and took up the position of assistant military engineer.

With scientific progress, especially in the field of astronomy, scientists have come up with a new mechanism for calculating distances, which is the standard candle index, which is a method based on knowing the type of luminosity emanating from stars. By calculating the time period of one cycle, scientists are able to deduce the distances between us and the stars in general.

Source: Al Jazeera + websites