Watch for Auroras


Those of you who remember my post on how to keep track of opportunities to see northern (and southern) lights will be impressed by this image from http://www.swpc.noaa.gov/communities/space-weather-enthusiasts .

The latest space weather overview plot

The top plot shows the number of X-rays (high-energy photons [particles of light]) coming from the sun, and that huge spike in the middle of the plot indicates a very powerful solar flare occurred about 24 hours ago.  It should take about 2 days from the time of the flare for its other effects — the cloud of electrically-charged particles expelled from the Sun’s atmosphere — to arrive at Earth.  The electrically-charged particles are what generate the auroras, when they are directed by Earth’s magnetic field to enter the Earth’s atmosphere near the Earth’s magnetic poles, where they crash into atoms in the upper atmosphere, exciting them and causing them to radiate visible light.

The flare was very powerful, but its cloud of particles didn’t head straight for Earth.  We might get only a glancing blow.  So we don’t know how big an effect to expect here on our planet.  All we can do for now is be hopeful, and wait.

In any case, auroras borealis and australis are possible in the next day or so.  Watch for the middle plot to go haywire, and for the bars in the lower plot to jump higher; then you know the time has arrived.

Filed under: Astronomy Tagged: astronomy, auroras



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