Northern Lights
Southern Lights, from Antarctica
Posted on 01/26/2019 11:22:26 AM PST by ETL
The northern lights (above) and their lesser-known sibling the southern lights, aurora borealis and aurora australis, respectively, undulate across the skies in hazy green and sometimes red ribbons near Earth’s polar regions. The two phenomena aren’t identical, however, and now researchers think they know why.
Aurorae appear as solar wind, a gust of charged particles emitted by the sun, blows across Earth’s magnetic field. Because the charged particles flow along symmetrical lines in Earth’s magnetic field linking the north and south poles, it made sense to assume the atmospheric displays in each hemisphere would mirror each other. Advances in Earth imaging technology overturned this way of thinking in 2009, when scientists observed simultaneous aurorae drifting across the poles in patterns that didn’t match up.
The study examined images of 10 asymmetric aurorae taken simultaneously from both poles and related changes in the aurorae to changes in Earth’s magnetotail, a windsocklike extension of Earth’s magnetic field. The researchers found that when solar wind approaches Earth from an east-west direction, it creates uneven pressure on Earth’s magnetotail and tilts it toward the side of the planet shrouded in darkness. That tilt causes the idiosyncrasies of shape and location of the northern and southern lights, the team reports this week in the Journal of Geophysical Research: Space Physics.
The findings could improve the prediction of solar storms—which can disrupt electricity grids, satellites, and astronauts in space, the team says. For now, though, observers can just appreciate these stunning—but distinct—light shows.
Northern Lights
Southern Lights, from Antarctica
Auroral displays appear in many colours although pale green and pink are the most common. Shades of red, yellow, green, blue, and violet have been reported. The lights appear in many forms from patches or scattered clouds of light to streamers, arcs, rippling curtains or shooting rays that light up the sky with an eerie glow.
What causes the Northern Lights?
The Northern Lights are actually the result of collisions between gaseous particles in the Earth’s atmosphere with charged particles released from the sun’s atmosphere. Variations in colour are due to the type of gas particles that are colliding. The most common auroral color, a pale yellowish-green, is produced by oxygen molecules located about 60 miles above the earth. Rare, all-red auroras are produced by high-altitude oxygen, at heights of up to 200 miles. Nitrogen produces blue or purplish-red aurora.
The connection between the Northern Lights and sunspot activity has been suspected since about 1880. Thanks to research conducted since the 1950’s, we now know that electrons and protons from the sun are blown towards the earth on the ‘solar wind’. (Note: 1957-58 was International Geophysical Year and the atmosphere was studied extensively with balloons, radar, rockets and satellites. Rocket research is still conducted by scientists at Poker Flats, a facility under the direction of the University of Alaska at Fairbanks - see web page http://www.gi.alaska.edu/
The temperature above the surface of the sun is millions of degrees Celsius. At this temperature, collisions between gas molecules are frequent and explosive. Free electrons and protons are thrown from the sun’s atmosphere by the rotation of the sun and escape through holes in the magnetic field. Blown towards the earth by the solar wind, the charged particles are largely deflected by the earth’s magnetic field. However, the earth’s magnetic field is weaker at either pole and therefore some particles enter the earth’s atmosphere and collide with gas particles. These collisions emit light that we perceive as the dancing lights of the north (and the south).
The lights of the Aurora generally extend from 80 kilometres (50 miles) to as high as 640 kilometres (400 miles) above the earth’s surface.
Where is the best place to watch the Northern Lights?
Northern Lights can be seen in the northern or southern hemisphere, in an irregularly shaped oval centred over each magnetic pole. The lights are known as ‘Aurora borealis’ in the north and ‘Aurora australis’ in the south. Scientists have learned that in most instances northern and southern auroras are mirror-like images that occur at the same time, with similar shapes and colors.
Because the phenomena occurs near the magnetic poles, northern lights have been seen as far south as New Orleans in the western hemisphere, while similar locations in the east never experience the mysterious lights. However the best places to watch the lights (in North America) are in the northwestern parts of Canada, particularly the Yukon, Nunavut, Northwest Territories and Alaska. Auroral displays can also be seen over the southern tip of Greenland and Iceland, the northern coast of Norway and over the coastal waters north of Siberia. Southern auroras are not often seen as they are concentrated in a ring around Antarctica and the southern Indian Ocean.
Areas that are not subject to ‘light pollution’ are the best places to watch for the lights. Areas in the north, in smaller communities, tend to be best.
When is the best time to watch for auroral displays?
Researchers have also discovered that auroral activity is cyclic, peaking roughly every 11 years. The next peak period is 2013.
Winter in the north is generally a good season to view lights. The long periods of darkness and the frequency of clear nights provide many good opportunities to watch the auroral displays. Usually the best time of night (on clear nights) to watch for auroral displays is local midnight (adjust for differences caused by daylight savings time). http://www.gi.alaska.edu/
Legends of the Lights
‘Aurora borealis’, the lights of the northern hemisphere, means ‘dawn of the north’. ‘Aurora australis’ means ‘dawn of the south’. In Roman myths, Aurora was the goddess of the dawn. \par Many cultural groups have legends about the lights. In medieval times, the occurrences of auroral displays were seen as harbingers of war or famine. The Maori of New Zealand shared a belief with many northern people of Europe and North America that the lights were reflections from torches or campfires.
The Menominee Indians of Wisconsin believed that the lights indicated the location of manabai’wok (giants) who were the spirits of great hunters and fishermen. The Inuit of Alaska believed that the lights were the spirits of the animals they hunted: the seals, salmon, deer and beluga whales. Other aboriginal peoples believed that the lights were the spirits of their people.
Gorons claim the change is due to climate discombobulations due to excess “see uh oh 2”.
*ping*
Then the article completely and utterly fails to tell us or show us why. What 8 year old wrote this?
Here is why northern and southern lights are different..
Northern lights are seen in the north and southern lights re seen in the south. Glad to clear that up!
Can you name a liquid that doesn’t freeze?
A: Hot water
Do you know why a Vee formation of geese has one line longer than another?
A: The longer line has more geese in it!
Sorry. Saw the article, posted it and ran, assuming it would have provided the answers. Was on a public PC and was close to timing out. I'll look at it more closely now.
They do seem to explain, but in a very convoluted way. A diagram or other visual would certainly have helped.
__________________________
"it made sense to assume the atmospheric displays in each hemisphere would mirror each other. Advances in Earth imaging technology overturned this way of thinking in 2009, when scientists observed simultaneous aurorae drifting across the poles in patterns that didn’t match up.
The study examined images of 10 asymmetric aurorae taken simultaneously from both poles and related changes in the aurorae to changes in Earth’s magnetotail, a windsocklike extension of Earth’s magnetic field.
The researchers found that when solar wind approaches Earth from an east-west direction, it creates uneven pressure on Earth’s magnetotail and tilts it toward the side of the planet shrouded in darkness. That tilt causes the idiosyncrasies of shape and location of the northern and southern lights"
I’m just grateful it wasn’t the result of man-made global warming.
I always wondered if it could be the difference between the positive pole and the negative pole flows of the magnet.
The researchers found that when solar wind approaches Earth from an east-west direction, it creates uneven pressure on Earth’s magnetotail and tilts it toward the side of the planet shrouded in darkness. That tilt causes the idiosyncrasies of shape and location of the northern and southern lights..."
Well, there’s the difference. The Educational Portal is only there for the Southern Hemisphere.
Believe it or not, a type of aurora borealis can be seen infrequently in the western desert of the Sudan.
I once saw them from New York City’s Central Park! I even caught a faint glimpse of the magnetic field lines.
The Van Allen belt is dangerous. It made Abin Sur crash on Earth. That is how Hal Jordan got his ring of power. I read that once. It must be true.
Thanks fieldmarshaldj.
That’s what gets me, no graphic? The problem here is that the author doesn’t understand any of this, either. He’s trying to interpret a press release from some scientific outlet (probably a university) and doing a crappy job of it.
This study only seems to be looking at a single snapshot in time. How about 6 months later, when the earth has moved to the opposite side of the sun and the poles have essentially switched positions (that is, their angles to the solar wind have swapped)? Do the northern and southern lights switch accordingly, too? It’s kind of appalling that the scientific group doing this study does not address that. Somebody forgot that the earth moves around the sun, it doesn’t just hang static in the same orientation all the time.
Also, there’s two times a year when the north and south poles are at the same angle to the solar wind. Do the northern and southern lights look the same at those two times or is there something else in play that keeps them different?
Lol! Exactly! And he/she was probably too embarrassed to admit they didn't understand and so didn't ask any clarifying questions.
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