Auroral displays are nothing new


Humans in far northern and southern latitudes have been observing auroral displays for as long as we have been humans. Cro-Magnon cave paintings in France and Spain dating to around 30,000 BCE look suspiciously like aurorae.

In the east, the first datable written record of an auroral display is in the Bamboo Annals, a historical chronicle of ancient China dating back to the 10th century BCE.

The first written record occurs in a Babylonian clay tablet from 567 BCE. The court astronomers of King Nebuchadnezzar recorded the lights in the sky as they carried out their official sky-watching duties.

The northern aurorae were well known to ancient Greeks and Romans despite their more southern latitude. The Greek philosopher Seneca (first century CE) not only describes aurorae but classifies them by their shapes — barrel-like (pithaei), chasms (chasmata), bearded (pogoniae), and cypress-tree-like (cyparissae).

The northern aurorae have a counterpart in the far south, the aurora australis. The first sighting by northern explorers is a subject of considerable historical controversy. The best-known observations happened on Sept. 16, 1770, during Captain Cook’s first voyage to Australia.

Joseph Banks and Sydney Parkinson observed the southern lights from the deck of Cook’s ship HMS Endeavour and recorded detailed accounts in their journals.

Significantly, Chinese observers described the northern counterpart of that southern auroral event on the same night in China. According to KKC Yau in his “Catalogue of Auroral Observations from China, Korea, and Japan,” it was recorded in the Chinese provincial histories of Hebei and Shandong Provinces.

However, an earlier sighting by Spanish naval officer Antonio de Ulloa was probably more significant. In 1745, he witnessed a southern aurora while rounding Cape Horn.

His report led French scientist Jean-Jacques Dortous de Mairan to conclude that the northern aurorae had a southern counterpart. That fact is an essential clue to the origins and structure of aurorae, but astronomers would only fully explore that clue during the dawn of the 20th century.

Our cluelessness about the causes of auroral displays produced sometimes charming and sometimes hair-raising stories, many of which concern death.

On the northern front, the Norse auroral mythology is the most developed. The Vikings believed that during every battle on Earth, Odin, the chief Norse god, picked the warriors who would die in a given battle and join him in Valhalla, the Norse heaven.

Female warriors called the Valkyries led the chosen dead to Valhalla. The auroral displays were the reflections of the Valkyries’ brilliant armor as they escorted the fallen warriors.

The Inuit people of North America assumed a rather spooky supernatural origin. They believed that the ghostly lights were indeed ghosts—the spirits of the dead playing soccer with the head of a Walrus. Parents warned their children that the ghosts might descend from the sky and snatch them away.

In the south, the indigenous peoples often tied the lights to the “spirit world.” The Dieri and Ngarrindjeri communities of South Australia view aurorae as bushfires generated by sky spirits. The Australian Gunai people see the “bushfires” as an indication of impending disaster.

The Indigenous people of Queensland regarded the phenomena as the “feast fires” of the Oola Pikka, ghostly ancestral spirits who used the aurora to communicate with tribal elders.

The aurora borealis didn’t get that name until the 17th century. Galileo Galilee observed an auroral display in 1621. It must have been a spectacular display, given that it was visible as far south as Italy.

As was the practice of the time, Galileo named the lights after Greco-Roman gods. Aurora was the goddess of the dawn, and red auroral displays can sometimes mimic the sunrise.

Boreas was the god of the northern wind, and the northern lights often appear in the north — when they appear at all in more southerly latitudes. Thus, a translation of aurora borealis might be something like “the northern dawn” to distinguish it from the daily eastern dawn.

Unfortunately, Galileo’s speculation about the causes of aurorae was utterly wrong. He believed that the aurora was sunlight reflected in Earth’s atmosphere.

However, Galileo was unaware of contemporary research that would eventually, after four centuries, lead to an explanation of the aurora’s ephemeral glow. More on that next week.

Tom Burns is the former director of the Perkins Observatory in Delaware.

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