Luckily, the Swedish Institute for Space Physics, located in Kiruna and with decades of scientific research into Northern Lights, can help us explain:
Centuries old Japanese drawings point researchers towards a better understanding of fan-shaped auroras
On September 17th, 1770, a magnificent magnetic storm —the largest of its type— lit up the skies over Earth. Its fan shaped created by light at the horizon, stretching into white fingers that spread wide across the sky. These narrow and tall streaks emitting light along obliquely inclined magnetic lines at regular intervals —infused with a red glow— creating a startling image of nature’s power and magnificence.
A drawing depicting the Aurora seen from Kyoto in September 1770. From the classic register «Star Solution» owned by Matsusaka City. Provided by Matsusaka City, Mie Prefecture.
The event was recorded not by scientists of the time or natural philosophers, but by artists across the world creating beautiful aurora paintings, white lines spread like fans with stunning red backgrounds.
One representation from the Kyoto area from Japan has sparked a quest that unites science and art, as physics researchers and scholars of art and literature have joined forces to forge a better understand the rare natural phenomenon of white and red auroras fanning across the night sky in Japan.
Armed with drawings and descriptions dating back to the 1700s, microfilm from the 1950s and modern-day spectral image data, the team have confirmed the accuracy of the older depictions. In the process, they have begun to form a better understanding of how the fan-shaped auroras appear–both in the sky and to the eye.
An illustration entitled «Aurora Borealis as observed on March 1, 1872 at 9:25 P.M.(Etienne Leopold Trouvelot (The New York Public Library Digital Collections)
Ryuho Kataoka is an associate professor at the National Institute of Polar Research and the Graduate University for Advanced Studies (SOKENDAI) in Tokyo (Japan) and the lead author of the paper. He says: «These phenomena are rare, but potentially disrupt man-made ground-based systems, including power grids.
«If we understand such auroras, it may help mitigate the possible natural hazard they could produce.»
During a magnetic storm, more charged particles are violently blown into the Earth’s outer atmosphere. As they crash into one another, the energized atmospheric particles lose energy because of emitting light.
Kataoka continues to explain some of the other events that his team are studying: «In the modern-day era, one of the strongest solar activities occurred in 1957. Auroras appeared over Japan several times in a few years around that event.»
Sample photograph (left, at 1044 UT) and hand-made sketch (right, at 1037 UT) of the auroras, as observed at Memambetsu Magnetic Observatory on February 11, 1958.(Japan Meteorological Agency)
On February 11, 1958, several Japanese meteorologists observed red auroras in northern Japan. Some took the first photographs of the fan-shaped auroras while others drew them.
Scientific analysis showed Kataoka and his team that the photographs caught more data than might be available to the human eye. Most strikingly, thin, green pillars dispersed throughout the aurora.
Kataoka continues: «It’s still challenging to understand the dynamic coupling between the space and atmosphere during the largest magnetic storms.”
The colours of auroras contain trace evidence of the nature of the particles impacting the upper atmosphere and where these collisions occurred. In addition to this, the motion of the auroras gives researchers clues about the active coupling between particles with a cosmic origin and those in the upper atmosphere.
All this helps us understand what happens when plasma infiltrates the atmosphere on a large scale. Equipped with this information, researchers may be able to determine the exact nature of the largest magnetic storms.
Coordinate transformation of the drawing sketched at the Meteorological Agency geomagnetic observatory Memanbetsu branch office at 7:00 pm on February 11, 1958. The centre is true north. The elevation and azimuth grids are 10 degrees apart.
In the next step for this research, Kataoka and his team plan to simulate the effects of space weather in the outer atmospheres during the special occasion of fan-shaped auroras and to reveal how they were created.
The study provides a fascinating example of art pointing the way in a scientific investigation of a phenomenon for which data is incredibly limited. Unlikely that as they painted these beautiful events, poorly understood even 200 years on, that the artists in question could have imagined they would be pointing the human race toward the stars in the distant future.
These results were published on May 17th in the Journal of Space Weather and Space Climate.
Si te ha gustado este artículo, puedes invitar al autor a un café o a lo que tú quieras. Gracias a tu contribución podremos seguir ofreciéndote las últimas noticias del arte contemporáneo en conexión con la ciencia y la tecnología
Freelance science writer based in UK. Graduated on physics, mathematics and quantum mechanics. Expert in Science Communication by the UK’s Open University.
The Crazy Superstitions and Real-Life Science of the Northern Lights
In 1859, a record-breaking aurora borealis shimmered across nearly the entire northern hemisphere and was visible as far south as Cuba. One of the witnesses to this historic heavenly display was the artist Frederic Edwin Church, who saw the event from New York City.
One of the 19th century’s most celebrated landscape painters, Church was also a “science nerd,” according to Eleanor Jones Harvey, the senior curator at the Smithsonian American Art Museum. In Church’s estimation, the study of science and the creation of art went hand-in-hand. “One of the things that makes Church so charming is that he did believe as an artist that you should also aspire to be a scientist and really know your material,” says Harvey.
A new episode of the museum’s web series “Re:Frame” takes a look at the dramatic convergence of solar science, arctic exploration, the Civil War and American art in Church’s 1865 painting Aurora Borealis.
During this unsettling time, anxiety and uncertainty hung like ether over a public that viewed these “nocturnal, unhinged rainbows,” as Harvey calls auroras in her book The Civil War and American Art, as divine omens.
“Auroras are weird, however, because they’re kind of a malleable portent,” she adds. “They can mean what you want them to mean.” For example, in the North, when the Union appeared to be winning the war, an aurora in the night sky was viewed as a talisman of God’s favor. By contrast, when the war seemed to be going in a less favorable direction, another aurora was deemed a portent of doom, a sign that the world was ending. In the absence of the scientific understanding of the phenomenon, these superstitious interpretations were given even more space in the collective understanding of the day.
Auroras are “a manifestation of what we now call space weather,” says David DeVorkin, the senior curator of the history of astronomy and the space sciences at the Smithsonian’s National Air and Space Museum. Just as meteorologists study conditions in our atmosphere in order to forecast the weather, space weather scientists study conditions in our solar system, some of which are known to produce effects visible on earth.
“The Earth’s atmosphere is reacting to very high energy particles coming from the sun, when the sun burps, you might say,” says DeVorkin. These particles are then caught by the Earth’s magnetic field, which “focuses them in the northern and very far southern latitudes.” The dynamic motion, characteristic of an aurora, is due to the fact that “the particles themselves are moving along,” he says.
“An aurora will wave, it will jump, it will flicker,” says DeVorkin, “They happen to be pretty.”
While the magnificence of auroras in Church’s time—well documented not only in newspapers, magazines and scientific journals but also in poems and, of course, art—resonates with us in the 21st century, the unsettling feeling that accompanied the presence of auroras during the Civil War era situates Aurora Borealis in an unparalleled historical moment.
When Frederic Church began work on this painting in 1864, says Harvey, “it’s not 100 percent clear that the Union is going to win. We don’t really know how this is going to turn out.”
In this way, the aurora that Church includes in his painting represents a dramatic tension like the one playing out in the drama of Hayes’s stranded ship—which was, fittingly, named the SS United States. What’s ultimately going to happen? Will the Union endure? And if so, what will the reunited United States look like? It’s all TBD.
Ultimately, Church’s Aurora Borealis is, Harvey points out, “a cliffhanger.”
Frederic Edwin Church’s 1865 Aurora Borealis is on view on the second floor, east wing of the Smithsonian American Art Museum in Washington, D.C.
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Anne Showalter is a Digital Interpretation Specialist at the Smithsonian American Art Museum.
Factors
The factors at play when the Northern Lights appear on Earth, or any planet:
- There needs to be an atmosphere as this is the “screen” on which the Aurora Borealis is projected. No atmosphere – no atoms for the particles to collide with!
- Secondly, there need to be charged particles or “plasma” that can transmit excess energy to the atoms.
- There needs to be a magnetic field that attracts the particles as they would otherwise just continue through space.
- You also need a “battery” or source of energy that can charge the particles. On Earth, that source is the Sun.
- Finally, you need to transfer the energy from the source to the particles in order to charge the particles. It is the solar winds that transport energy from the Sun to the particles.
Photo Tomas Jönsson
Solar winds, solar storms
In order for the charged particles in space to reach the high speed that is required to create Northern Lights, they need the energy from the Sun. The solar wind consists of protons and electrons discharged from the Sun at a speed of 400 km per second. These particles are collectively called plasma.
Plasma is kind of gas, but there is one significant difference. Gas has no electric energy whereas plasma does. In gas, all electrons (negative energy) and protons (positive energy) are organized in atoms and there are equally many of both kinds so they balance each other. Also, atoms have neutrons which are not charged at all.
The Earth creates a barrier for the solar wind. Most of the plasma in the solar wind travel around the Earth, kind of how water travels past a rock in a stream.
The solar wind envelops the magnetic fields of the Earth in a bubble, creating our magnetosphere that works as a shield against particles traveling in space. Planets with magnetic fields have magnetospheres, but other space objects and even entire galaxies can have them as well.
Every second, the edge of the magnetosphere, the magnetopaus, is hit by enourmous amounts of energy. Of all this energy, only a small fraction filters through to the atmosphere, and an even smaller fraction becomes visible as Northern Lights.
A magnetic substorm (solar storm), is an interruption in the magentic field. These interruptions take place in the Auroral Oval and are caused by changes in the magnetic field and charged particles within it. The storm lasts about 10-30 minutes and afterwards the Northern Lights are usually extra strong.
What Northern Lights look like – arch, band, coronas
Aurora Borealis can appear in many different shapes. Early at night, it is usually a grand arc stretching across the sky from east to west. Usually it is green and with fuzzy edges. The bottom of the arc is quite sharp while the upper edge is blurred.
Sometimes, the arc can be active and start moving so it looks like curtains. You may see rays of light that appear in the same direction as the Earth’s magnetic field. The length of the arc can reach up to 1000 km or more, while its width can be limited to as little as 100 m.
An aurora band is similar to an arc but crimped or curled into a spiral.
If you stand right underneath the northern lights in the same direction as the magnetic field, the Aurora rays appear to originate from one single point and radiate outwards. This is called a corona.
If you are watching the same Northern Lights, but from a location further south or north, it will appear as an arch.
The most intense Northern Lights, which appear after solar storms, the entire sky can be filled by incredible shapes and colors including green, red, blue and violet. On these occasions, the light can be strong enough to read a text in a book or magazine.
The shades and shapes change very suddenly. The most intense activity may not last more than 10 minutes so the trick is to check the sky often!
When the extra energy transmitted to the magnetosphere from the solar storm is reducing, you may see pulsating Northern Lights. Underneath, you may see pale patches of light appearing and disappearing randomly and with different duration but usually only a few seconds. These types of Northern Lights are most common after midnight.
The most common Aurora is called “Different” Northern Lights. They are difficult to see because they lack shapes and may just appear as a soft glow over big sections of the sky.
In fact, there is always Northern Lights somewhere on the sky even if you can’t see it. Around the Earth’s magnetic poles there is always a ring of Aurora but you may be in the wrong location. Or, you may be in the right location but still can’t see it because of clouds, daylight or bright summer nights.
