The active region on the Sun (AR1748) that fired off four powerful X-class solar flares in less than 36 hours earlier this week erupted again Friday morning, producing a moderate flare, but this time unleashing an immense coronal mass ejection (CME) aimed towards Earth.
The flare, which ranked as magnitude M3.2, was only a tenth as powerful as the X3.2 flare from Monday night. However, it when it erupted, its source — the sunspot-studded area called 'Active Region 1748' (AR1748) — had rotated around onto the side of the Sun facing Earth, so the resulting ribbon of solar material that whipped out along the flare's magnetic field lines and then snapped, launching off into space, was aimed more or less directly at us.
NASA's Solar Dynamics Observatory (SDO) and Solar and Heliospheric Observatory (SOHO) captured the flare and coronal mass ejection:
Although solar flares bombard the Earth with X-rays and coronal mass ejections represent billions of tons of solar matter streaming towards us, these pose no direct danger to us. Our atmosphere is thick enough that it protects us against X-rays, and the charged particles in a coronal mass ejection are deflected by the Earth's magnetic field.
However, all of those charged particles impacting on the magnetic field can spark intense geomagnetic storms, which can have a damaging effect on satellites, give astronauts in orbit a stronger radiation dose, and even people flying in aircraft near the poles can receive a small dose of radiation as well.
[ More Geekquinox: NASA sees brightest impact on the moon on record ]
With all this 'X-class' and 'M-class' and 'coronal mass ejection' jargon floating around this week, Science@NASA released a video presentation to explain the science and terminology about these events:
One thing that these coronal mass ejections do for us is create spectacular auroras at the poles. With this one expected to arrive sometime tonight or Sunday, it could cause the Aurora Borealis and Aurora Australis to be particularly intense this weekend.
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