Northern Lights: 8 Surprising Auroras Facts

Northern Lights: 8 Surprising Auroras Facts
Northern Lights: Auroras 

The northern lights, or aurora borealis, are a spectacular display of the Earth’s magnetic field interacting with charged particles from the sun. It’s also stunning, and it’s worth risking a chilly night out if you’re in the high northern (or southern) latitudes.

Auroras are visible in a roughly circular zone surrounding the Earth’s magnetic poles. Because the magnetic and geographic poles aren’t the same, auroras can be seen farther south than one might think, and farther north in other areas. 

The auroral zone stretches along the northern coasts of Siberia, Scandinavia, Iceland, the southern point of Greenland, and northern Canada and Alaska in the Northern Hemisphere. Auroras can be seen to the south of the zone, but they are less likely to appear to the north. The auroral zone in the Southern Hemisphere lies largely over Antarctica or the Southern Ocean. The southern lights (or aurora australis) can only be seen in Tasmania, and there are rare sightings in southern Argentina or the Falkland Islands. Here are some fascinating facts regarding these light displays.

1. Different ions produce distinct hues.

   Aurora displays are produced when protons and electrons from the solar surface collide with the Earth’s magnetic field. Because the particles are charged, they move in spirals along the magnetic field lines, with protons moving in one direction and electrons moving in the other. These particles, in turn, collide with the atmosphere. Because they follow magnetic field lines, the majority of them penetrate atmospheric gases in a ring around the magnetic poles, where the magnetic field lines intersect.

The air is mostly composed of nitrogen and oxygen atoms, with oxygen being a larger component at the altitudes at which auroras occur — beginning at around 60 miles and continuing all the way up to 600 miles. When charged particles collide with them, they gain energy. They eventually relax, releasing photons of specified wavelengths and releasing energy. Oxygen atoms emit green and occasionally red light, whereas nitrogen emits more orange or red light.

2. They can be seen from space.

Satellites can photograph the aurora from Earth’s orbit, and the results are rather stunning. In fact, auroras are brilliant enough that they may be seen clearly on the nightside of the Earth even if viewed from another planet.
The International Space Station’s orbit is so inclined that it even passes across the heavens. Because the density of charged particles is so low, most of the time no one notices. According to Rodney Viereck, director of the National Oceanic and Atmospheric Administration’s (NOAA) Space Weather Prediction Test Bed, the only time it matters is during exceptionally powerful solar storms, when radiation levels are high. At that moment, the astronauts only need to shift to a more secure region of the station. (Ironically, since charged particles interact with the Earth’s magnetic field, powerful solar storms can actually lessen the quantity of radiation around the space station.) Meanwhile, ISS astronauts may capture stunning auroral panoramas.

3. They exist on other worlds.

The Voyager 1 and 2 probes were the first to return images of auroras on Jupiter and Saturn, and subsequently Uranus and Neptune. The Hubble Space Telescope has also captured images of them since then. Auroras on Jupiter and Saturn are significantly bigger and more powerful than those on Earth because their magnetic fields are orders of magnitude stronger.
Because Uranus’ magnetic field is aligned approximately vertically, yet the planet turns on its side, auroras become more bizarre. That implies that, rather than the dazzling rings seen on other planets, Uranus’ auroras appear more like single bright spots, as seen by the Hubble Space Telescope in 2011. However, it is not apparent that this is always the case, because no spacecraft has seen the planet up-close since 1986.

4. The lights have the ability to migrate south.

Occasionally, the auroras can be seen further away from the poles than normal. During periods of strong solar activity, the southern limit for observing auroras can extend all the way to Oklahoma and Atlanta, as it did in October 2011. When the northern lights shone during the Civil War during the Battle of Fredericksburg in Virginia in 1862, a record was most likely made. Many troops made a note of it in their journals. Viereck claims that it is actually more difficult to identify when auroras are particularly bright today than it was a century ago since so many Americans live in cities, and the lights wash out the aurora. “You might have a tremendous auroral storm in New York City and not see it if you didn’t look up,” he remarked.

5. Divine signs?

Speaking of the Civil War aurora, some interpreted it as a negative portent (particularly Elizabeth Lyle Saxon, who wrote about it in her 1905 book, “A Southern Woman’s War Time Reminiscences”), but most merely saw it as an uncommon and spectacular spectacle. In locations where the lights are uncommon, they were frequently interpreted as ominous omens, as the ancient Greeks did. The Inuit, who view auroras more frequently, believed the lights were spirits playing in the sky, and some clans would warn youngsters not to play outside at night for fear the aurora would vanish and take them with it. The lights were supposed to be the souls of the dead by the Lapplanders. Maori and Aboriginal Australians live in the Southern Hemisphere.

6. icy fire

The northern lights appear to be fire, but they do not feel like it. Despite the fact that the high atmosphere may reach hundreds of degrees Fahrenheit, heat is generated dependent on the average speed of the molecules. After all, temperature is what it is. The density of the air is so low at 60 miles (96 kilometers) up that a thermometer would detect temperatures much below zero where aurora displays occur.

7. Cameras have a better view of it.

Auroras are weak, and the redder light is frequently near the limit of what human retinas can detect. Cameras, on the other hand, are frequently more sensitive, and with a long-exposure setting and a beautiful black sky, you may get some stunning images.

8. It is impossible to foresee a spectacle.

Knowing the form of a magnetic field in a coronal mass ejection (CME), which is essentially a big blob of charged particles released from the sun, is one of the most challenging topics in solar physics. CMEs of this type have their own magnetic fields. The difficulty is that it is nearly impossible to identify which way the CME field is pointing until it impacts. A strike either causes a stunning magnetic storm and a beautiful aurora, or it fizzles. There is currently no way to know ahead of time.

NOAA offers an online map that can show you what auroral activity looks like on any particular day, as well as the extent of the “auroral oval” and where it is more likely to occur.

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