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| © Liz Carlson |
March 19, 2015 - NEW ZEALAND - A severe geomagnetic storm has whipped through Earth's magnetosphere, putting on a light show at both ends of the earth.
The storm, which began on Tuesday, is among the strongest in the
current 11-year solar cycle, earning a rating of a "severe" G4 on a
one-to-five scale, which means it had the potential to affect power
grids, high-frequency communications and satellite operations.
Interestingly, there was no radiation storm, which typically accompanies
geomagnetic storms of this magnitude. Therefore, NOAA's Space Weather
Prediction Center was not expecting disruption to satellite electronics
or polar-routed aviation.
But the changes in density in the
ionosphere - the very high levels of Earth's atmosphere - could cause
more drag on low-orbit satellites, which operators may have to adjust
for with thrusters. Simple GPS technology, like the kind in your car or
on your smartphone, could be affected in the form of difficulties
locating your position.
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| The Aurora Australis, or Southern Lights, in the sky at Himatangi Beach on Tuesday night, March 17. © Stephen Chadwick |
The
solar wind was not particularly fast, but it was potent enough to cause
the severe geomagnetic storm, according to Joe Kunches, director of
space weather services at Atmospheric and Space Technology Associates.
Quick & Dirty all sky timelapse of last night's Aurora Australis over Dunedin. https://t.co/grEmccCUTt #Dunedin #aurora
— Ian Griffin (@iangriffin) March 17, 2015
Happy Saint Patrick's Day! Green from space. We have @Space_Station aurora views:
https://t.co/UG1x2YutsO pic.twitter.com/FBpXJ5OIhd
— NASA (@NASA) March 17, 2015
Rendering 300 frames takes a while doesn't it! Meanwhile, here's another still from last night. #Dunedin #aurora pic.twitter.com/KWqHLnrEjA
— Ian Griffin (@iangriffin) March 17, 2015
There's a stunning aurora over Crowborough, East Sussex tonight. The view from the Wetherspoons car park is magical. pic.twitter.com/nLfMzMGqNg
— Nick Harvey (@mrnickharvey) March 17, 2015
Solar storm smacks Earth, pushes northern lights — so more people can enjoy colorful sky show http://t.co/7ESH5nGvHD pic.twitter.com/Dvi3SZtwLB
— CBS News (@CBSNews) March 17, 2015
The
storm's strength came as somewhat of a surprise to forecasters and was
probably caused by the combination of two coronal mass ejections from an
active sunspot region, forecasters at the prediction centre said.
Space weather models predicted just a "glancing blow" from these
ejections, which instead have caused a stronger disruption here on
Earth, and vivid auroras.
Sunspots full of high magnetic energy
frequently explode and send plumes of radiation called solar flares
into space. When these flares and the super-heated plasma that can
accompany them interact with Earth's magnetic field, radioactive energy
sometimes makes it into the Earth's upper atmosphere.
These
particles can interfere with radio communications and global positioning
systems, and when strong enough, they can even harm the electrical
grid. But they do have at least one positive effect: The impact of the
particles with the upper atmosphere creates a beautiful glow that we
know as the northern lights.
Because the Earth's magnetic field
funnels charged particles from these solar storms towards its poles,
polar regions are much more likely to be affected by them. That's why
the auroras are most frequently seen at the poles and rarely make it to
North America, as they have this week.
Solar cycles are
periodic changes in the sun's activity, including the number of sunspots
and solar flares, that have an average duration of about 11 years. They
are marked by solar maximums and minimums. The sun is currently close
to the solar maximum of this cycle, which began on January 4, 2008, and
likely peaked in April 2014.
The Space Weather Prediction
Center, part of the National Oceanic and Atmospheric Administration,
ranks the intensity of geomagnetic storms on a G-scale of one to five,
with five being the strongest. According to the centre, on average
around 100 G4-magnitude storms occur every solar cycle. This is the
first G4 storm since the fall of 2013. There hasn't been a G5 storm -
the strongest on the scale - since August 2005.
The current storm is in season, so to speak, since they are most common around the equinoxes.
Research as to why solar storms are more common and severe around the
equinoxes is still ongoing, but it most likely has to do with the way
the Earth's position relative to the sun changes. The Earth's
orientation changes what parts of its magnetic field are interacting
with the sun's, making those interactions more volatile.
North Island Aurora
Central North Island residents were seeing pink as the Southern Lights, or Aurora Australis, lit up the sky.
The Aurora Australis is usually only visible in southern New Zealand
but was clear in the skies over Himatangi Beach in the Manawatu when
resident Steve Chadwick snapped some pictures before midnight.
Chadwick, who teaches astronomy and philosophy at Massey University and
dabbles in astrophotography, said he was out taking pictures from about
9pm.
"You need a dark sky away from the city lights and you have to be able to have a long exposure," he said.
"At this latitude they're a lot fainter than in the pictures but at best you could see faint red."
As someone who's lived in the Manawatu for most of his life, this was
only the second time he'd ever seen the lights so it was a special
moment, he said.
Travel blogger Liz Carlson captured the
stunning sky from Wanaka. "Last night you could see beams of light
dancing over the mountains around Wanaka and you had every colour
visible, red, yellow, pink purple and green. It was pretty spectacular
to see. This was shot with a 15 second exposure from Eely Point looking
over Lake Wanaka around 11pm."
Palmerston North Astronomical
Society president Jeremy Moss said the colourful light phenomena was
caused by charged particles, like protons, neutrons, ions and electrons,
being released from the sun and hitting the Earth's atmosphere.
"The closer you are to the pole, so north and south, the more likely you are to see it," he said.
"We don't see it very often in the north of New Zealand unless there's
some pretty serious solar activity going on so we were pretty lucky last
night."
He said the lights were reasonably common in Southland and they usually didn't last for more than several minutes. -
Stuff.
