Chance of Thanksgiving Day Solar Flare, Aurorae?


UPDATE (11/22): NOAA space weather forecasters believe AR1618 could generate an X-class solar flare — the region has a “delta-class” magnetic field, a configuration that has enough energy to produce the most powerful of solar eruptions. Stay tuned…

The sun is currently a hive of magnetic activity and it has been putting on quite a show. As reported by, only a few days ago, active region (AR) 1618 was nothing more than a dot on the solar landscape — it has since grown into a monster, spanning 10-times wider than the Earth’s diameter. What’s more, it has rotated across the sun’s equator to point right at us.

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AR1618 is currently crackling with flare activity. Yesterday, it even popped off a M1.6-class flare, generating an extreme-ultraviolet flash captured by NASA’s Solar Dynamics Observatory (SDO) — pictured right. This flare, and one preceding it, may have generated a weak coronal mass ejection (CME), but the plasma from that event won’t likely hit the Earth’s magnetosphere until Friday.

It seems likely that AR1618 flare activity will continue through Thanksgiving, and if you live at high latitudes, you may be lucky enough to see some Thanksgiving Day aurorae. The sun is currently bathing our planet in a moderate-speed stream of solar wind. Although a full-blown geomagnetic storm isn’t expected, there’s a chance of some heightened auroral activity near the Arctic Circle.

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This intense period of solar activity isn’t unexpected; it’s all part of the natural solar cycle that ebbs and flows over an approximate 11-year cycle. The peak of this cycle, called “solar maximum,” is expected in 2013, but in the run-up to the crescendo, the sun has been increasingly active.

Solar max represents a period when the sun’s magnetic field is at its most stressed, so magnetic features like coronal loops and prominences are often observed in the sun’s atmosphere (the corona). Explosive events like CMEs and flares also become commonplace. The solar wind — a stream of charged particles that constantly flow into interplanetary space — also becomes amplified.

All of these factors can impact our planet’s magnetic field, increasing the chances of radiation and geomagnetic storms — magical light shows in the form of aurorae are often a result of this geomagnetic battle. Solar storms can also impact our increasingly high-tech society, a fact not lost on the world’s space weather prediction efforts.

Image: Top: Today’s sun as seen through the SDO’s 304A filter — AR1618 is the bright region nearest the center of the sun’s disk. Middle: Tuesday’s M-class flare as seen through several of the SDO’s filters. Credit: NASA/SDO

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