If a total solar eclipse is the grandest celestial spectacle, then a good display of the Northern Lights comes in as number two. Both involve the Sun, of course. And both are being delivered to us just a couple of weeks apart.
At 5:10 a.m. EDT on Wednesday (September 6) an X-class solar flare—the most powerful Sun-storm short of a ten-billion-ton “coronal mass ejection”—erupted from an enormous sunspot near the center of the Sun. Then, in a seeming game of one-upmanship, it was dwarfed three hours later by an even stronger flare—the greatest seen in 11 years.
An X9.3 class solar flare flashes in the middle of the Sun on Sept. 6, 2017. This image was captured by NASA’s Solar Dynamics Observatory and shows a blend of light from the 171 and 131 angstrom wavelengths
Ever since 1859, when a British astronomer became the first to see a solar flare, astronomers have been observing these violent solar events, and been in awe of their power.
Some disrupt Earth’s radio communications and can even damage satellites.
But the “bright side” is that many flares are accompanied, a few days later, by impressive displays of the aurora borealis.
The debris from this week’s monster solar flare hit Earth’s magnetic field last night. The result: Northern Lights in the USA as far south as Arkansas.
NOAA computer models show a ring of aurora-energy circling the Arctic.
It very much matters where the solar flare is located. If its position is just to the right (or west) of the Sun’s middle, then the broken atom fragments it hurls into space can follow the solar magnetic field and have an easy path to our planet. And this is exactly where this flare erupted.
You may be able to see the sunspot from where the flare erupted, if you still have those solar eclipse that you used on August 21. Those filters can be used to look at the Sun anytime.
The Sun’s rotation makes sunspot storms move slightly to the right day by day, so for the next few days, look for a tiny black spot on the right side of the Sun.
But don’t wait: By mid-September the Sun’s one-month rotation will have carried the sunspot off the edge and around to the back side, where it will be visible only to some of the many solar-monitoring satellites maintained by NASA.
To sum up: Look for any suspicious glows in the northern sky the next few nights. A truly powerful aurora might be seen from anywhere in the US, although the majority of major displays are only viewable from Canada, Alaska, and the northern half of the country. And keep checking out the Sun directly. But only through those filters, of course.