"We seem to be ideally located in the Canadian Prairies for sighting Steve, as we often get the main aurora to our north, placing Steve overhead or to our south," notes Dyer.
A strong geomagnetic storm was brewing in the skies above Alberta, Canada, on Sept. 27th when photographer Alan Dyer looked up and saw a ribbon of purple light arcing cross the sky. It was the mysterious aurora known as "Steve":
"The Steve arc appeared for only about 20 minutes, starting at 10:45 pm MDT, during a lull in the main display," says Dyer, who captured the arc in a 6-shot, 360o panorama.For many years, northern sky watchers have reported this luminous form occasionally dancing among regular auroras. It was widely called a "proton arc" until researchers pointed out that protons probably had nothing to do with it. So members of the Alberta Aurora Chasers group gave it a new name: "Steve."
"We seem to be ideally located in the Canadian Prairies for sighting Steve, as we often get the main aurora to our north, placing Steve overhead or to our south," notes Dyer.
No one fully understands the underlying physics of the purple ribbon. One of the European Space Agency's Swarm satellites flew straight through Steve during a previous apparition. Data revealed a relatively hot river of gas, about 25 km wide, flowing rapidly through Earth's outer atmosphere. "Steve seems to be a thermal emission from hot flowing gas rather than from precipitating electrons," says Dyer, "but his origin and nature are still mysterious." www.spaceweather.com
GEOMAGNETIC STORM PREDICTED: NOAA forecasters say there is a 75% chance of moderately strong (G2-class) geomagnetic storms on Sept. 13th. That's when a CME hurled into space by a powerful X8-class solar flare on 10 September will likely deliver a glancing blow to Earth's magnetic field. The impact of the CME could be enhanced by a fast-moving solar wind stream, expected to arrive at about the same time. If the G2-storm materializes, auroras in the USA could appear as low as New York to Wisconsin to Washington state.
SOLAR RADIATION STORM AND GROUND LEVEL EVENT: On Sept. 10th, departing sunspot AR2673 erupted, producing a powerful X8-class solar flare. The explosion propelled a CME into space and accelerated a swarm of energetic protons toward Earth. Both are visible in this coronagraph movie from the Solar and Heliospheric Observatory (SOHO):
(go to http://spaceweather.com/ to watch animation)
The many specks in this movie are not stars--they are solar protons striking SOHO's digital camera. Almost two days later these protons are still streaming past our planet, causing a moderately strong (S2-class) solar radiation storm. The latest data from SOHO show an ongoing blizzard of digital "snow" in coronagraph images:
What made this flare so 'radioactive'? It has to do with the location of AR2673 at the time of the explosion. The sun's western limb is magnetically well-connected to Earth. Look at this diagram. Magnetic fields spiraling back from the blast site led directly to our planet, funneling these energetic protons Earthward.
Normally, solar radiation storms are held at bay by our planet's magnetic field and upper atmosphere. On Sept.10th, however, there was a "ground level event" (GLE). Neutron monitors in the Arctic, Antarctic, and several other high latitude locations detected a surge of particles reaching all the way down to Earth's surface:
The Bartol Research Institute's South Pole Neutron Monitor detected a GLE on Sept. 10th.
"In historical terms, this was a relatively small ground level event-- only about one thousandth as strong as the event of 23 Feb 1956, which is the largest measured," says Clive Dyer, a Visiting Professor at the University of Surrey Space Centre.
However, that does not mean the Sept.10th GLE was negligible. Dyer says that "passengers flying on high-latitude routes at 40,000 feet could have absorbed an extra 10 microSieverts of radiation. During the first hour of the GLE, the dose rate inside the aircraft during such a flight would have approximately doubled."
He also notes that the GLE could have caused minor upsets of onboard electronics and avionics, although nothing on the scale of the epic 1956 GLE, "which would be very challenging to modern systems."
"Since measurements began around 1942 there have now been 73 events detected by ground level radiation monitors," Dyer adds. "The Sept.10, 2017, event is far from the strongest, but it is of special interest because it demonstrates the need for continual vigilance even during Solar Minimum." www.spaceweather.com
Last night in Otago, New Zealand, Ian Griffin counted more than a dozen "aurora sprites" dancing over Hoopers Inlet. "The display was very beautiful," says Griffin, "with ghostly auroral sprites putting on a display that lasted for several hours."
Also known as "picket fence auroras," these vertical rays trace lines of magnetic force connecting Earth to space. The luminous columns show where beams of energetic particles are being guided toward Earth's upper atmosphere by magnetic fields.
The solar wind stream that instigated the display has produced many enchanting auroral forms since March 1st. Browse the realtime gallery for more. www.spaceweather.com
In the Lofoten Islands of Norway, Spaceweather.com reader Rob Stammes operates a magnetic observatory. Twenty-four hours a day, he measures the strength and direction of the local magnetic field as well as electrical currents running through the ground. During geomagnetic storms, his chart recordings go haywire. On Jan. 13th, something different happened. They rang like a bell:
"For about an hour, electrical currents in the ground beneath my observatory flowed back and forth with a sinusoidal period near 2 minutes," says Stammes. "This is rare."
These are natural ultra-low frequency oscillations known to researchers as "pulsations continuous" (Pc). The physics is familiar to anyone who has studied bells or resonant cavities. Earth's magnetic field carves out a cavity in the surrounding solar wind. Gusts of solar wind can make the cavity "ring" akin to a bell (references: #1, #2, #3). Human ears cannot hear this ringing; it is electromagnetic rather than acoustic. The physical effect is felt beneath our feet. As the cavity vibrates, magnetic fields swing back and forth, causing electrical currents to flow through the ground below.
The Pc waves Stammes detected are a variety known as Pc4, which oscillate in the frequency range 6.7–22 mHz. Such waves are good at energizing particles trapped in Earth's magnetic field and often cause local outbursts of bright auroras. www.spaceweather.com
Similar occurrences were also reported on 12 September and 23 October 2016:
http://www.ascensionnow.co.uk/quick-info/-earths-magnetic-field-rings-like-a-bell - 12 Sept. 2016
http://www.ascensionnow.co.uk/quick-info/sinusoidal-ground-currents-in-norway - 23 Oct. 2016
What do Christmas Eve, Christmas, and Boxing Day 2016 have in common? They were days without sunspots. Throughout the holiday weekend, the face of the sun was completely blank, and the sun itself looked like a big orange Christmas ornament:
Including Dec. 24th, 25th and 26th, 2016 has had 31 'spotless days'--a whole month's worth. We haven't had this many blank suns in a single year since 2010 (51 days). This is a sign that the sunspot cycle is crashing toward a new Solar Minimum.
There are many misconceptions about Solar Minimum. One holds that auroras vanish when sunspots disappear. Christmas Day 2016 was proof that the opposite is true. Without a hint of a sunspot on the solar disk, intense auroras raged around the Arctic Circle on Dec. 25th. What caused the luminous outburst? An enormous hole in the sun's atmosphere directed a stream of solar wind toward Earth, sparking a week-long display that is still underway. Such atmospheric holes are common during Solar Minimum, which is a fine time to see Arctic auroras.
Many people think space weather becomes dull or stops altogether during Solar Minimum. In fact, space weather changes in interesting ways. For instance, as the extreme ultraviolet output of the sun decreases, the upper atmosphere of Earth cools and collapses. This allows space junk to accumulate around our planet. Also, the heliosphere shrinks, bringing interstellar space closer to Earth; galactic cosmic rays penetrate our atmosphere with relative ease. Yes, Solar Minimum is coming ... but it won't be dull.
Six days after Earth entered a stream of high-speed solar wind ... we're still inside. The solar wind continues to blow faster than 500 km/s on Oct. 31st. Although it is not as gusty as it was during first contact on Oct. 25th, the relentless pressure of the sun's electrically charged wind on Earth's magnetic field is causing the poles to glow with beautiful auroras. Marketa S. Murray sends this picture from Fairbanks, Alaska, on Oct. 29th:
"When you stand there and the whole sky is just dancing overhead, your adrenaline and endorphin get so high," says Murray. "It's mind blowing every time it happens. It never gets old, even for an Alaskan!"
Until Earth fully exits this stream, polar auroras remain likely. A good way to follow the action is to tune into a live webcam in Sweden's Abisko National Park. "We have seen the lights nearly every night in October!" says Chad Blakley of Lights over Lapland, who operates the camera.
Watch it now. www.spaceweather.com
During this week's solar wind event, observers around the Arctic Circle reported auroras of an unusual color. "Crazy pink," says Frank Meissner, who photographed the phenomenon on Oct. 26th from Tromsø, Norway:
"It was awesome," he says. "Flash-like bursts were zooming all over the sky."
Watching from Tromsø on the same night, veteran observer Terence Murtagh says "even with many hundreds of aurora sightings under my belt, I've never witnessed such distinct pink colors clearly visible and bright to the naked eye. They were almost too bright to photograph properly."
The pink color is probably a sign of nitrogen. Most auroras are green--a verdant glow caused by energetic particles from space hitting oxygen atoms 100 km to 300 km above Earth's surface. Seldom-seen pink appears when the energetic particles descend lower than usual, striking nitrogen molecules at the 100 km level and below. More examples may be found in the realtime photo gallery: Realtime Aurora Photo Gallery
A strong G3-class geomagnetic storm is underway on Oct. 25th as Earth enters a stream of solar wind flowing from a coronal hole on the sun. First contact with the stream produced a magnificent outburst of auroras over Alaska. Marketa S. Murray sends this picture from Fairbanks AK:
"The storm finally hit," says Murray, "and the auroras were unbelievable."
More auroras are in the offing tonight as the solar wind is blowing faster than ~700 km/s. Around the Arctic Circle, the Northern Lights should be quite bright. Lesser displays could cross the Canadian border into the United States.
In the Lofoten Islands of Norway, Spaceweather.com reader Rob Stammes operates a magnetic observatory. 24 hours a day, he measures the strength and direction of the local magnetic field as well electrical currents running through the ground. During geomagnetic storms, his chart recordings go haywire. On Sept. 12th, something different happened. They rang like a bell:
"During the morning and especially around noon, sinusoidal pulsations appeared on my instruments," says Stammes. "The period was close to 115 seconds."
These are natural ultra-low frequency oscillations known to researchers as "pulsations continuous" (Pc). The physics is familiar to anyone who has studied bells or resonant cavities. Earth's magnetic field carves out a cavity in the surrounding solar wind. Pressure fluctuations in the solar wind can excite wave modes in this cavity much like Stammes observed. References: #1, #2, #3.
The Sept. 12th oscillations are Pc4 waves; in other words, their frequencies fall in the range 6.7–22 mHz. Pc4 waves, and their even lower frequency cousins Pc5 waves (1.7–6.7 mHz), can have an energizing influence on particles in Earth's inner magnetosphere because the waves resonate with the natural motion of particles around the geomagnetic field. Perhaps it is no surprise, then, that bright auroras were observed on both Sept. 11th and 12th.
Ole Salomonsen photographed these from the window of an airplane just before sunrise in Norway:
"To get the shot was not easy," says Salomonsen. "I had to use a handheld camera in a moving plane! To create some darkness, I draped one of my jackets to over me and the window to prevent cabin-light reflections ruining the shot. The people sitting next to me probably must have had a good laugh :) Anyway I think it was worth it. Observing the auroras from air is definitely special."
Rob Stammes has been monitoring magnetic pulsations in Norway for years. "They seem to occur most often around the equinoxes," he says. That means we should stay tuned for more. It is aurora season, after all.
Toby Meyjes : Metro.co.uk : 23 Feb 2016
© Hallgrimur P. Helgason/Caters
These dramatic images of the aurora borealis appear to show a phoenix rising from the ground
What do you reckon? Is this mesmerising image up there with the best recent pictures taken of the Northern Lights? Shot in Iceland, it shows what looks like a huge phoenix with wings outstretched rising in to the night's sky. It was captured by photographer Hallgrimur P. Helgason in Kaldársel, who said he had been shooting for an hour when the mythical creature appeared.
'It's really a thrill shooting the aurora, especially when they are so playful like they were that night,' said the 64-year-old. 'I have to admit that I always get an adrenaline kick when the lights burst out like that - that particular shot was the top one of the night.'
Hallgrimur uses a camera and tripod to photograph the lights and advises snapping in the dark away from city light pollution and never using a flash. He said that the Northern Lights were mainly showing in green and yellow colours when he was shooting that night but also sported red and blue suggesting that the aurora was strong.
Geomagnetic storms are brewing, but not every colorful light in the night sky is an aurora. For instance, Yuri Beletsky sends this picture taken Dec. 17th from the Atacama desert in Chile:
"These are not auroras. We just witnessed an amazing display of airglow," says Beletsky. "It was so intense that you could not see many stars close to the horizon - the sky was literally shining."
Airglow is an aurora-like phenomenon in the upper atmosphere caused by a variety of chemical reactions. It begins during the day when solar ultraviolet radiation ionizes atoms and molecules. At night, those same atoms and molecules glow as they re-capture lost electrons. The green in Beletsky's photo comes from oxygen atoms in a layer 90-100 km high; the red is probably associated with OH ions at an altitude of about 85 km. The wavy structure of the glow is due to high-altitude gravity waves, which alter the temperature and density structure of the upper atmosphere.
"Airglow is much less intense than aurora," continues Beletsky. "The display I saw looked, to the naked eye, like a series of black-and-white waving bands. The full color of the display was easily captured, however, by my digital camera."
For reasons researchers don't fully understand, auroras love equinoxes. At this time of year even a gentle gust of solar wind can spark a bright display. Tomorrow, Sept.23rd, is the northern autumnal equinox. Perfect timing: a CME is expected to deliver a glancing blow to Earth's magnetic field on Sept. 23rd. The impact will probably be weak, but on the first night of autumn, weak may be strong enough. High-latitude sky watchers should be alert for equinox auroras. www.spaceweather.com
On Sept. 1st, astrophotographer Yuri Beletsky hiked into the Atacama Desert of Chile for a deep exposure of the Milky Way. He got that and much more. "There was a stunning display of red airglow," he says. It surrounded the [centre of the] Milky Way like a celestial bulls-eye:
Airglow is aurora-like phenomenon caused by chemical reactions in the upper atmosphere. Human eyes seldom notice the faint glow, but It can be photographed on almost any clear dark night, anywhere in the world.
The curious thing about Beletsky's photo is not the presence of airglow, but rather its color--red. Airglow is usually green, the color of light from oxygen atoms some 90 km to 100 km above Earth's surface. Where does the red come from? Instead of oxygen, OH can produce the required color. These neutral molecules (not to be confused with the OH- ion found in aqueous solutions) exist in a thin layer 85 km high where gravity waves impress the red glow with a dramatic rippling structure.
"It was a truly special night," says Beletsky. "Pure tranquility."
A surprisingly strong G3-class geomagnetic storm erupted on Aug. 15th when a CME hit Earth's magnetic field. Two nights later, as the storm was subsiding, midnight sky watchers in North America witnessed a rare and beautiful form of aurora--a "proton arc." Paul Zizka photographed the phenomenon on Aug. 17th from Banff, Alberta (see below, left). "It was incredible," says Zizka. "The whitish pillar remained nearly stationary for over 30 minutes--enough time for a self-portrait."
In Val Marie, Saskatchewan, photographer Sherri Grant saw a purple proton arc cutting across the Milky Way. And in Oroville, Washington, at the Table Mountain Star Party, campers witnessed at least two more arcs (see below, centre and right).
Ordinary auroras are caused by electrons, which rain down on Earth's atmosphere from above. Atoms of oxygen and nitrogen, excited by the pitter-patter of electrons, form dynamic curtains of light. Protons have a different effect. For reasons not fully understood, protons normally trapped in our planet's ring current sometimes rain down on Earth's atmosphere during geomagnetic storms. En route, they excite a type of plasma wave called "EMIC"--short for electromagnetic ion cyclotron waves. The result is not a curtain, but rather a tight arc of light as shown above.
Many of the photographers who witnessed proton arcs on Aug. 17th have been observing auroras for years, yet they had never seen this phenomenon before. Geomagnetic storms still have the capacity to surprise!
Sunday, Dec. 21st is the northern winter solstice. At 6 pm EST, the sun will reach its lowest declination in the celestial sphere, -23.5 degrees, marking the start of winter and the longest night of the year at northern latitudes. The long night could be filled with auroras. NOAA forecasters estimate a 65% chance of polar geomagnetic storms in response to glancing blows by one or two CMEs. Happy solstice!
_This section is for interesting items which are brought to my attention but which do not merit a separate article.
I welcome your comments, questions or suggestions on any topics you wish to contribute to this section.
Link to: Contact and