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Tuesday, June 25, 2019

The Great Aurora of 1859

Northern Lights
On the evening of September 2, 1859, after the sun went down on the western hemisphere, a spectacular show of light began on the skies above. Streams of luminous cloud in blue, green, purple and sometimes red shot upwards from the horizon in the north and filled the entire sky. Many people thought that there was a large fire burning somewhere. Others took it as a sign from the heavens of some great disaster that’s about to befall man. Few realized what they were looking at, because many of them had never seen the Northern lights before, and never will.
The day before, the first of September, was warm and sunny, and British astronomer Richard Carrington was looking at the sun through his telescope in his “well-appointed private observatory.” The telescope was trained to project an 11-inch-wide image of the sun on a screen, and Carrington was skillfully drawing the sunspots he saw. For the past few days, Carrington was keeping track of a large and complicated group of sunspots on the solar disc. As Carrington was making observation that day, he noticed two dots of intensely bright light appear over the sunspots, that intensified rapidly and took the shape of a kidney bean. After reaching a maximum intensity, the bright dots began to fade and disappeared five minutes after Carrington first noticed them. Carrington did not know what it was, but he realized it was something of enormous importance.
Richard Carrington
Sunspots of September 1, 1859, as sketched by Richard Carrington.
By happenstance, another British astronomer, Richard Hodgson, was also observing the Sun at the same time that morning and he too observed what is now known as a solar flare. It was the first time anybody had ever witnessed a solar flare, and it so happened that the solar flare of September 1, 1859, was a very powerful one. But that was hardly a coincidence. Most flares require special filters to be seen from Earth, and these equipment had not been invented at that time. Only the most intense flare, like the one seen by Carrington and Hodgson, is visible in the visible spectrum.
Eighteen hours later, the mass of charged particles ejected from the sun hit earth and bathed the entire blue planet in aurora so bright that one could read a newspaper as easily as in daylight. So intense was the solar storm that the aurora was visible all over North America, even as south as the Caribbean. In the Southern hemisphere, thousands of people witnessed the grand display from south-central Mexico, Queensland, Cuba, Hawaii, and even from latitudes very close to the equator, such as Colombia.
solar storm
A magnificent solar storm erupted out into space on August 31, 2012. This image was captured by the Solar Dynamics Observatory satellite.
Newspapers the following day featured glowing reports about aurora that turned night into day.
For the first time in several years we had last night a grand exhibition of the ‘Northern Lights’,” wrote San Francisco Daily National. “The light was so brilliant that it shone on Telegraph Hill and the upper story and cupola of Wright’s building like the reflection of an extensive conflagration. The light, or rather columns of light, were of a deep red hue, and at one time extended from the horizon almost to the zenith.”
Vivid streams of light shot up from the horizon in the north, extending from east and west, which were at times red, and presented the appearance of the reflection from a large fire. The atmosphere was so strongly illuminated that it appeared as if the moon were shining, and rays of light, resembling the rays from the sun as reflected upwards from the back of a cloud, continued to be brilliantly visible during the whole time,” came the report from The London Morning Post.
The horizon from north to north east became of a deep crimson hue, which expanding slowly, made the sky appear as if lighted by a Bengal fire. At first it was supposed that some great conflagration had taken place on the outskirts of the city, but it was soon recognized that no natural firs could produce this particular hue,” observed the New Orleans Daily.
The dazzling visuals were also accompanied by large-scale havoc. Telegraph systems across the world went haywire as sparks flew from equipment, giving electric shocks to operators, and setting papers on fire. An employee at Boston’s telegraph office discovered that he could disconnect the batteries powering the lines and still transmit and receive messages from Portland, using aurora-induced electric currents in the wires. The Daily Chronicle and Sentinel reported that the system actually worked better without the batteries connected.
To date, the aurorae seen in September, 1859, was the most intense in the last 160 years. If a solar storm of such intensity were to hit earth today, it would cause widespread disruption of the high-tech infrastructure that underlie pretty much every modern convenience we use today—the power grid, the internet, mobile networks, telephone networks, television signals, even urban water supplies. Satellites would be knocked out, including GPS, which has become ubiquitous with cell phones but is also indispensible for essential services such airplane and marine navigation. Airplanes will be grounded, banking transactions will not take place, and even critical equipment in hospitals would stop working. A Carrington-class solar storm “could effectively send the world back to the Dark Ages,” says Science Alert.

Earth was almost struck by a storm of such ferocity in July 2012. The large cloud of hot plasma went through the earth’s orbit but missed the planet by only nine days. According to Daniel Baker of the University of Colorado, the storm was as powerful as the one in 1859. “If it had hit,” said Baker, “we would still be picking up the pieces.”

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