Sunday, January 22, 2012

Monster Plasma "Blob" Headed for Earth: Is This the End?

Top: Plasma eruption occurring on the Sun. Bottom: a magnificent green aurora of the type that may be visible in many locations this evening.

In the grade B -minus 1992 science fiction movie (Solar Crisis) with Charlton Heston, a massive catastrophe was depicted in a future time when the Earth is threatened by an impending "mega" flare and plasma burst. The energy outburst was forecast to "tear away the atmosphere and shower deadly radiation on everything". We'd end up little better than the hapless humans depicted in the more recent scifi flick, "KNOWING".

Now, we have word from that a monster plasma burst has erupted from the Sun and is headed our way. Do we have cause to worry from either this event or any powerful flares that might follow it?

First, the energy of flares is limited by how much "free" (extractable) energy can be stored in the magnetic tubes that spawn them. A good analogy is a rubber band. If a rubber band is wound up over and over it gains free potential energy (available for future motion). Release it now and it will rapidly twist apart to its original state. Magnetic tubes on the Sun do something very similar. They are twisted up by the motions of the Sun's turbulent surface and store free magnetic energy as they twist. The more twisted they are, the more free magnetic energy they acquire - to power flares, and the particle bursts that accompany flares.

Second, not all powerfully twisted magnetic tubes are enabled to release all their energy at once. Sometimes it's released in lesser bursts, maybe coronal mass ejections, or lesser flares of lower intensity.

Flare energy is limited because: 1- there is a limit to the size a magnetic tube can attain, 2- there is a limit to how much twist a tube can acquire. Each of these limits the amount of total magnetic energy available for release. On that basis, it is unlikely that humans will ever see flares greater than those which occurred in August, 1972 and March, 1989. In the latter case, the Ottawa power grid was briefly knocked down as its main conducting wires literally melted. Note, however, that these are extreme cases.

What is heading for us is not the high energy radiation (mainly gamma -UV radiation) of a monster flare as such but rather the plasma from a "CME" or coronal mass ejection. So what is the most we might expect?

As reported at spaceweather:

"A coronal mass ejection (CME) hit Earth's magnetic field at 0617 UT on Jan. 22nd. At first the impact did not appear to be a strong one: the solar wind speed barely lifted itself to ~400 km/s when the CME passed by. Now, however, in the wake of the CME, a dense and increasingly geoeffective solar wind stream is blowing around Earth, setting the stage for possible auroras on the night of Jan. 22nd"

This means there is an excellent chance of seeing some spectacular auroras tonight, perhaps as far south as Florida and Texas. Generally, when such powerful plasma-generated currents impinge on our atmosphere, we can expect these to be translated into powerful sky displays of the northern lights.

So, instead of being overwrought by pseudo-fear (there'll be plenty of time for that later, as the "Mayan Apocalypse" approaches) maybe we all just need to chill out and try to catch some of the bright natural fireworks likely to go off tonight!

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