Magellanic Clouds
Categories: AstronomyHistoryMagellanic Clouds
A History of the Magellanic Clouds and How They Got Their Names
Image of the night sky taken at the European Southern Observatory's Very Large Telescope in Chile. The Large and Small Magellanic Clouds are visible in the night sky. Credit: ESO, Y. Beletsky
The Magellanic Clouds are a pair of dwarf galaxies that are bound to the Milky Way. The Milky Way is slowly consuming them in Borg-like fashion, starting with the gas halo that surrounds both Clouds. They're visible in the southern sky, and for centuries people have gazed up at them. They're named after the Portuguese explorer Ferdinand Magellan, in our current times.
But they weren't always called that.
They had other names in the past, and those names point to the history of the Magellanic Clouds and of the explorers that ventured into the southern hemisphere. New published research explores that history.
The new research paper is titled "A History of the Magellanic Clouds and the European Exploration of the Southern Hemisphere." The sole author is Michael Dennefeld of the Institut d'Astrophysique de Paris. The paper is at the pre-press site arxiv.org.
Ferdinand Magellan is most well-known for being the first European to discover a sailing route to the Spice Islands by sailing East. That voyage began in 1519, 500 years ago, and resulted in the first circumnavigation of the globe, though Magellan was killed in battle during the long voyage and never returned to Europe. (Note: There is some debate and some popular misunderstanding around Magellan and his voyage, which you can read about here.)
During that historic voyage, Magellan and his fleet of five vessels and about 270 men "discovered" the Strait of Magellan, though indigenous people had inhabited the area for thousands of years, and obviously already knew about it. Magellan originally named the sea route Estrecho de Todos los Santos ("Strait of All Saints"). But later, Charles V, who financed Magellan's expedition, changed the name to Strait of Magellan to honor him.
The Strait of Magellan provides safe sea passage between the Atlantic and the Pacific Oceans, the only safe way until the construction of the Panama Canal. It's protected by Tierra del Fuego to the south, and by South America to the north. Image Credit: By Jacques Descloitres, MODIS Rapid Response Team, NASA/GSFC – http://visibleearth.nasa.gov/view_rec.php?id=6092Transferred from the English Wikipedia originally here, Public Domain, https://commons.wikimedia.org/w/index.php?curid=35059
Magellan's name was also given to the two dwarf galaxies, also to honor him. But not at first. It took a while before they bore his name.
The Magellanic Clouds were visible to early peoples in the southern hemisphere. Petroglyphs and rock drawings in Chile are the earliest preserved representations of them, and they're mentioned in ancient Islamic texts, too.
And in the age of exploration, every sailing ship carried an astronomer/navigator, who couldn't have failed to notice the Clouds. Despite that, written records aren't plentiful. In fact, one of the earliest written accounts of the Magellanic Clouds came from Magellan's voyage itself. His chronicler Antonio Pigafetta wrote:
"The Antarctic pole has no star of the fate of the Arctic pole, but we see many stars congregated together, which are like two nebulae, a little separated from each other, and a little dark in the middle. Among these there are two, not very large nor very bright, which move little: and those two are the Antarctic pole." (Translated from Italian).
Magellan and Drakes's historic sailing voyages. Image Credit: Dennefeld, 2020.
In his paper, author Michel Dennefeld says there are likely two reasons why there are few written accounts.
The first reason is that navigators were looking in the southern sky for something like the North Polar Star, which they could use to measure their latitude. The Magellanic Clouds didn't serve that purpose. Secondly, many travel accounts from sailing expeditions were kept secret. European powers were competing with each other, and they kept their valuable information to themselves.
This brings us to the central point of Dennefeld's new work. According to Dennefeld, "… to understand the "history" of the Clouds, one needs to follow the history of discoveries and travel in the south, and also the history of the mapping of the southern sky by European explorers and
astronomers."
Naturally, it all begins with the peoples who were native to the area. Unfortunately, they had no written language, and everything was transmitted orally. There's the aforementioned petroglyphs, but they're just representations of the night sky with no commentary.
Still, some oral knowledge has persisted. According to the paper, the Tupi-Guarani people, in the region of Rio de Janeiro in Brazil, compared the Magellanic Clouds to fountains, with either a tapir (in the LMC) or a pig (in the SMC) drinking from it. Sticking with the water theme, the Mapuche people in Chile compared the Clouds to ponds of water.
Magellan's name will grace one of our most powerful telescopes soon. This illustration shows what the Giant Magellan Telescope will look like when it comes online. The fifth of its seven mirror segments is being cast now. Each of the segments is a 20 ton piece of glass. Image: Giant Magellan Telescope – GMTO Corporation
In his paper, Dennefeld explains how the Mapuche people understood the Magellanic Clouds: "There were initially three ponds, but one has already dried out (the Coal Sack ?), a second one is presently on the way to dry out (the SMC) and when the last one (LMC) will also become empty, it will be the end of the Universe!" Coal Sack refers to the Coal Sack Nebula, a dark nebula that dominates the southeast corner of the Crux constellation. Interestingly, the Coal Sack Nebula was also called Magellan's Spot, or the Black Magellanic Cloud.
It was the Arabs that first travelled systematically to the South. They travelled down the east coast of Africa, and also directly to India. There are several nautical sources that date from this time, from both Arabs and Persians. That knowledge was precious, and Vasco de Gama made use of it when he crossed the Indian Ocean in 1498. Those sources used several stars in the southern sky for navigation, but they never used the Magellanic Clouds: they were too diffuse.
The Chinese also would have seen the Clouds when they navigated around India to reach the Arab world, whom they had longstanding ties with. But at around 1425 to 1435, the new Chinese Emperor began to cut China off from those ties and became more insular. Unfortunately, the Emperor ordered that all records from sailing voyages to India be destroyed. So we'll never know what those accounts held.
It was probably the Portuguese who were the first western explorers to see the southern sky. In 1455, Alvise de Ca'da Mosto travelled to the river Gambia. That's at about 13 degrees North. He mentioned the Southern Cross, but not the Clouds. They may not have been easy to see in July, when he was there.
Navigators used the Southern Cross to find South, but often they never mentioned the Magellanic Clouds, even though they're right there.
So the first reference to the Clouds by a western explorer is from Amerigo Vespucci, from 1501-2 during his third voyage. Vespucci's Mundus Novus is written correspondence to his patron, outlining some of his experiences and observations. In it he wrote "And among the others I saw three Canopes: the two were very clear, the third was dark and unlike the others." (Translated.) Vespucci is clearly referring to the Large and Small Magellanic Clouds and the Coalsack Nebula.
Around 1515, Italian explorer Andrea Corsali travelled to Cochin on the southwest coast of India. He wrote two letters describing his experiences and the southern sky. In one he wrote: "Where is the Antarctic pole, … and evidently two clouds of reasonable size (the Clouds), which around it continuously now lowering and now getting up in circular motion they walk, with a star always in the middle, which with them yes it turns away from the pole about eleven degrees."
According to Dennefeld, this was the first clear representation of the Magellanic Clouds.
Corsali also made some drawings, showing the Southern Cross and the two Clouds, with the star y Hyd.
On the left is a partial map of the Southern Sky with showing the LMC (middle right) and the SMC (bottom middle). On the right is Andrea Corsali's sketch from 1515, showing the clouds and y Hyd. Image Credit: Left: By Roberto Mura – Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=11736512.
This is where Dennefeld's account turns to Magellan and his voyages. Thanks to Antonio Pigafetta's presence, and thanks to him surviving the historic voyage, we know quite a bit about that expedition. But that was a long time ago, and history being what it is, things have a way of going missing. Pigafetta's original report disappeared, but several translations survived.
In one of those surviving translations Pigafetta wrote: "The Antarctic Pole is not so starry as the Arctic is. Because we see several stars small congregations (packed) together, which are in the guise of two clouds one
little separated from each other, and a little offended (obscured), in the middle of which are two stars not too big nor very shining and which move slowly. And these two stars are the Antarctic Pole." Unfortunately no sketch accompanies this description.
Dennefeld explains that Pigafetta wasn't an astronomer, or even a navigator. That was partly good, because his writing was much more lively, contributing to its lasting this long. The writings of the many astronomers and navigators who went on these voyages was much drier, and hasn't lasted as long. That's one of the obstacles to piecing together this history.
Magellan's chief pilot was Andrès de San Martin. He was killed during the voyage, but his writings survived for a time at least. Another writer wrote a report on the voyage based on San Martin's log books, but it seems to contain some errors and misrepresentations, especially around the timing of eclipses that the crew observed. In fact, San Martin's descriptions seemed to have made their way into several reports by others, but the Magellanic Clouds are never mentioned.
A portrait of Ferdinand Magellan by an unkown artist. Magellan never survived his historic voyage, and was killed in battle. Image Credit: By Unknown author – The Mariner's Museum Collection, Public Domain, https://commons.wikimedia.org/w/index.php?curid=44265
The fact that they're not mentioned is important to Dennefeld: "Once again, this provides proof that the main interest was initially to find stars able to mark the southern celestial pole but not to map the sky, and even this approach was largely abandoned once the solar technique <of deriving latitudes> had been mastered."
In his paper, Dennefeld recounts the many voyages by European explorers to the southern hemisphere. They began to map the sky in earnest, though at first Magellan's name wasn't used. The former scientific names of Nubecula Minor and Nubecula Major were used. As the decades and centuries rolled on, the cartogaraphy of the sky became more and more detailed.
In 1679, Edmund Halley published published the Catalogus Stellarum Australium, his catalog of Southern Hemisphere Stars, based on his observations taken at the island of St. Helena. That work shows that astronomers still called the Clouds Nubecula Minor and Major, but points out that sailors were calling them the Magellanic Clouds. "It appears it was clear to him that the name Magellanic Clouds was used only by sailors, and
that those Clouds resemble the Milky Way," writes Dennefeld.
By the early 1750s, the Clouds were becoming more commonly known as the Magellanic Clouds, or the Clouds of Magellan. French Astronomer Nicolas de La Caille observed the southern sky from the Cape of Good Hope, and he wrote that "In fact, most Navigators call Cape Clouds, what we call clouds of Magellan, or the big & the little cloud." (D'ailleurs, la plupart des Navigateurs appellent nuages du Cap , ce que nous appelons nuées de Magellan, ou le grand & le petit nuage.)
Dennefeld writes about de La Caille that "… his words, "que nous appelons nuées de Magellan", seem to indicate that around that time the association of the Clouds with Magellan was already spreading beyond the nautical community, even if the scientific term was still simply Nubeculae or les Nuages."
Enlargement of La Caille's map of 1752, showing the 2 Clouds (red arrows;
Paris Observatory.)
However, Dennefeld also writes that two comprehensive observations of the southern sky in the 1820s and 1830s made no mention of the Magellan Clouds.
As the account comes to more modern astronmers like John Herschel, things shift again. In 1847, Herschel was the first one to use the name Magellanic Clouds in a scientific publication, alongside the scientific names of Nubecula Major and Minor.
Herschel's drawing of the Large and Small Magellanic Clouds. In the drawing he calls them the Magellanic Clouds, but in the text he uses the scientific names. Herschel, London, 1847.
This is where Dennefeld's work ends. In our time, the Magellanic Clouds are just that, and the scientific name is hardly ever heard. And our knowledge of them is more detailed than Magellan or any of the ancient seafarers could have imagined.
We know that they're separate dwarf galaxies, and that the Milky Way is slowly drawing them in and consuming them. So in a way, the ancient observers were sort of half-right. They are made of the same stuff the Milky Way is, but rather than being separated pieces of it, they're actually slowly joining it. That's something they could never have figured out.
The ancients would be amazed at what we know about the Magellanic Clouds in our time. For instance, we know that the Milky Way is slowly consuming them, starting with a stream of gas from the Clouds' halo. Link: NASA Press Release
We know that the Magellanic Clouds are gas-rich and metal-poor compared to the Milky Way. We know that it's rare for them to be this close to our galaxy. And we know that the Milky Way's gravity is distorting their shape.
And now, thanks to Dennefeld, we know more about the history of their names.
New Research: A History of the Magellanic Clouds and the European Exploration of the Southern Hemisphere
Wikipedia Entry: Magellanic Clouds
Universe Today: Enjoy The Biggest Infrared Image Ever Taken Of The Small Magellanic Cloud Without All That Pesky Dust In The Way
Evan Gough
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Tags: Age of ExplorationExplorationFerdinand Magellanhistoryhistory of astronomyLarge Magellanic CloudnavigationSmall Magellanic Cloud
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