Geomagnetic Storm Aurora Alert

Tonight into tomorrow, northern hemisphere sky watchers as far south as Iowa or Michigan to Washington State are on aurora alert. Auroras are caused by charged particles hitching a ride on solar wind, dark skies turn undulating curtains of mischievous colour when charged particles interact with molecules in our atmosphere. Usually, our magnetosphere acts as a planetary shield preventing geomagnetic interaction of charged particles. Every so often fast moving particles overwhelm our magnetic field, create an opening and light up night skies.

On May 12, a magnetic filament on the sun, seen here, became unstable and erupted. (NASA/SDO)

Since Monday, 3 additional solar eruptions sent fast moving charged particles our way. As a result the auroral oval (doughnut shaped ring around the pole where charged particles follow magnetic field lines, reason why far northern latitudes regularly witness geomagnetic storms), has shifted far to the south.

The northern lights as seen looking eastward from just east of Penzance, Sask., at 1:21 a.m. local time Tuesday morning. (Submitted by Notanee Bourassa)

The colour of that light depends on the kind of molecule and the altitude of the collision.

Green is the most common colour, produced when the particles collide with oxygen at an altitude of around 100 to 300 km. At about 300 to 400 km, the interaction with oxygen produces red. Pink occurs below 100 km when nitrogen atoms are struck.

This link – is worth a ponder. One of the best I’ve found in terms of understanding what makes space weather tick.

Bottom line – Space Weather Prediction Centre forecasters say there’s a 75% chance of geomagnetic storm activity tonight. If your skies are clear, go outside. If she’s willing, Aurora will find you. Opportunities like this don’t come along every day.


Solar Sector Boundary Crossing

Hang on for a lesson in solar dynamics – Earth is experiencing a solar sector boundary crossing. Let me explain….

The sun produces wind (currently 410.9 Km/second) that blasts across the cosmos. Just like Earth, our Sun has a magnetic field – known as the interplanetary magnetic field (IMF).  Whipped into a spiral rotation, wind driven IMF rotates in one direction. It divides into spiral sections pointing to and away from the sun along the ecliptic plane ( a direct line between Earth and the Sun). The edge of this swirling mass has a surface separating polarities of planetary and solar magnetism called the heliosphere current sheet.

Earth’s magnetic field points north at the magnetopause (the point of contact between our magnetosphere and the IMF). If the IMF happens to point south at contact (scientific term, southward Bz) the two fields link causing partial cancellation of Earth’s magnetic field – in other words, opening a temporary door for solar energy to enter our atmosphere. Welcome solar sector boundary crossing – a phenomenon born of high solar wind and coronal mass ejections (CME’s – aka solar flares).

It takes 3 or 4 days for magnetism to sort itself out – in the meantime, and barring the occasional high frequency radio disruption,  wonky GPS and cell phones, peppered with sudden power grid failure events – we’re treated to kick ass auroras.

Aurora Alert Tonight

Ponder Earth’s magnetic field as a shield protecting us from harmful cosmic radiation. Known as “geomagnetic” because it starts at our solid iron outer core, (miles below the surface) and reaches to the outer atmosphere. (creating a magnetosphere, the point in space beyond the ionosphere where charged particles protect us from solar wind and radiation). Without it – our ozone layer would wither, and we would succumb to ultraviolet radiation. In other words, life could not exist.

When strong solar winds impact the magnetosphere, they “distort” our magnetic field creating “openings” – the near side to the sun being “compressed” and far side of the planetary field is bulged outward.

  1. As the charged particles of solar winds and flares hit the Earth’s magnetic field, they travel along the field lines.
  2. Some particles get deflected around the Earth, while others interact with the magnetic field lines, causing currents of charged particles within the magnetic fields to travel toward both poles — this is why there are simultaneous auroras in both hemispheres. (These currents are called Birkeland currents after Kristian Birkeland, the Norwegian physicist who discovered them — see sidebar.)
  3. When an electric charge cuts across a magnetic field it generates an electric current (see How Electricity Works). As these currents descend into the atmosphere along the field lines, they pick up more energy.
  4. When they hit the ionosphere region of the Earth’s upper atmosphere, they collide with ions of oxygen and nitrogen.
  5. The particles impact the oxygen and nitrogen ions and transfer their energy to these ions.
  6. The absorption of energy by oxygen and nitrogen ions causes electrons within them to become “excited” and move from low-energy to high-energy orbitals (see How Atoms Work).
  7. When the excited ions relax, the electrons in the oxygen and nitrogen atoms return to their original orbitals. In the process, they re-radiate the energy in the form of light. This light makes up the aurora, and the different colors come from light radiated from different ions.

Two recent solar events – CME’s (coronal mass ejection) are poised to deliver Aurora magic in regions unaccustomed to their magnificence. Solar wind from the first eruption have arrived, with stronger consequences from the second ejection expected in the next few hours. What this means is Auroras could be visible far below normal latitudes. Some scientists project as far south as Mexico.

If you feel so inclined – go outside, cast your gaze northward, and watch for tell tale green ripples across the sky. Best time to view is between midnight and dawn – obviously clear skies away from city lights are advisable.

Taken a few hours ago from the International Space Station







Starfish Prime

July 9, 1962 – 250 miles above uninhabited Johnston Island – a Pacific atoll between Hawaii and the Marshall Islands –  America detonated a nuclear warhead. As part of “Operation Fishbowl”, this wasn’t their first high altitude nuclear rodeo. High altitude nuclear testing began in 1958.  six detonations that year raised more questions than answers.  Hardly surprising poor instrumentation and inconclusive data, frustrated scientists on the forefront of nuclear exploration.

“Previous high-altitude nuclear tests: YUCCA, TEAK, and ORANGE, plus the three ARGUS shots were poorly instrumented and hastily executed. Despite thorough studies of the meager data, present models of these bursts are sketchy and tentative. These models are too uncertain to permit extrapolation to other altitudes and yields with any confidence. Thus there is a strong need, not only for better instrumentation, but for further tests covering a range of altitudes and yields.” – Defense Atomic Support Agency interim report on Starfish Prime, August 1962

Just after 11 PM Honolulu time July 9, 1962, Thor (the first USAF ballistic missile) unleashed Starfish Prime – Thor traveled almost 700 miles straight up before puttering out, as it fell towards Earth – at precisely 13 minutes 41 seconds after launch –  a programmed detonation took place around the 250 mile mark.

The question of how Earth’s magnetosphere reacts to thermonuclear assault became clear. The EMP (electromagnetic pulse) sent instruments off the scale, 900 miles away in Hawaii streetlights blew, burglar alarms sounded and a damaged telephone microwave link knocked out phone service between Kauai and other Hawaiian Islands. Auroras illuminated thousands of miles over the Pacific – according to a U.S. Defense Report, the New Zealand Navy on anti-submarine maneuvers, took advantage of light from the blast. Starfish created a “radiation belt”  – initially 3 “low earth orbiting” satellites went dark, ultimately a third of all “low earth” satellites clocked out. It would be 5 years before Starfish electrons completely left our atmosphere.

Starfish Prime was the last high altitude nuclear event – science wasn’t prepared for such a powerful EMP, further detonations would have been folly. A clever decision to place tracer isotopes in the package, allowed science to  map polar and tropical air masses.



Magnetic Crochet

This is what happens when a solar eruption hurls energy our way at 11 million mph. Sunspot AR2017 erupted on March 29 with a healthy X-1 class flare – UV radiation ionized our upper atmosphere, resulting in a “ripple” in Earth’s magnetosphere. Known as a “magnetic crochet”, the disturbance occurred as AR2017 strutted her stuff –  geo-magnetic hiccups usually come knocking a few days after a flare – simultaneous “events” are rare.

For a short time radio signals were lost as static assaulted short wave operators.

Courtesy NASA’s Solar Dynamics Observatory – a video of AR2017 in action….

AR2017 appears to have gotten it off her chest – simmering down with only a 55% chance of M and 20% chance of powerful X class activity in the next 24 hours. Dodging yet another cosmic EMP unscathed.

Scientists at Berkley have just released findings of a global “near miss” on July 23, 2012. A series of immense solar flares unleashed enough energy to rival the Carrington Event of 1859. Had the storm erupted 9 days earlier, our planet would have been in the cross hairs – global power grid failures, trillions of dollars in economic repercussions with an estimate of 4 – 10 years to recover.