A Sputtering Sun Could Mean Auroras May 15-16

Active region 2741 (right) has been the seat of exciting magnetic activity in recent days which could bring aurora to our skies on May 15 and 16. This photo was taken at 12:30 p.m. CDT today. NASA / SDO

I sure wish I’d been up at 3 o’clock this morning. That’s when a surprise aurora hit. In a very short time, conditions went from a minor G1 storm to a strong G3. For several hours until around 6:30 a.m. CDT, the storm would have been visible (before twilight grew too bright) across the northern third of the U.S. Things have quieted down now, but more is on the way.

A loop of hot hydrogen gas called a prominence hovers over the edge of the sun. When seen in silhouette against the sun (see below), a prominence is called a filamentNASA / SDO

Multiple coronal mass ejections (CMEs) from the region around sunspot group 2741 on May 10, 12 and 13 are headed in Earth’s direction as you read this. The pileup should arrive over the next two days — May 15 and 16 — and produce minor to moderate (G1-G2) geomagnetic storms.  CMEs are clouds of protons and electrons shot into space at over a million miles an hour. A solar flare can launch a CME. So can instabilities in magnetic fields surrounding sunspots.

Now you see, now you don’t. Two views taken about 19 hours apart show the disappearance of the large filament near the big sunspot in region 2741. National Solar Observatory / Mauna Loa

On May 12 over a period of hours, a dark filament of incandescent hydrogen gas erupted and left the sun headed in our direction. Filaments are just prominences — those fiery pink “flames” we see around the edge of the sun during a total solar eclipse — seen in silhouette against the bright solar surface. A filament looks like an eyelash when viewed through a specialized filter. Filaments “body surf” atop invisible magnetic fields. When those fields become unstable, they can launch the filament into space.

The sun connives to rattle the Earth and its inhabitants in many ways, so keep your eyes peeled for northern lights the next few nights. There’s just one caveat — the moon. It’s getting bigger and brighter with each passing night. Its light not only washes out fainter auroras but illuminates the thicker, denser air near the horizon, mimicking the glow of a low auroral display.

A classic start to an auroral display — a low, pale green arc low in the northern sky. Here the lights glow beneath the Big Dipper. Bob King

A display usually starts as a low arc or glow about a fist or 10° above the northern horizon. You’ll know if you’re seeing aurora by shape and movement. Auroras come in arcs and vertical streaks, not the formless “blooms” of city light pollution that blot our horizons nowadays. FYI, horizontal streaks are almost always clouds. Watch for movement. If you see a glowing patch disappear and then reappear in the same area, that’s the aurora. If a patch slowly drifts in one direction, it’s a cloud.

You can always get the latest 3-day spaceweather forecast here, which describes activity every 3 hours by a Kp number from 0 to 9. A “5” is a minor storm; a “6” a moderate one and a “7” a strong storm. Also, be sure to check the extent of the aurora to see if it’s spreading southward in your direction at the 30-minute forecast site. This site shows the extent of the northern and southern auroral ovals, permanent rings of aurora centered on Earth’s geomagnetic poles.

Clear skies would be nice. Let’s hope we get them.

3 Responses

  1. kevan hubbard

    Spied some pseudo aurora tonight.probably high whispy cirus catching the Sun which at this time of year isn’t too far under the north west horizon.no noccullient clouds that I could see although perhaps a wee bit early in the year and I’m now a full 3 degrees south of where I saw them last year in ,I think?, June?I think anyone over about 45 degrees north,and I’d guess south too although not many people live that far south,can see them.be interesting to know if people have seen noccullient clouds from Tasmania and New Zealands South island I’ve never seen pictures of them from there but have see aurora pictures mainly from Tasmania.invercargil,n.z.and Hobart, Tasmania,look to be about 46 degrees south whereas usuhuia, Argentina is much further at nearly 55 south.

    1. astrobob

      Hi Kevan,
      Yes, I’ve seen noctilucent clouds on occasion here at 47°N. Infrequent though.For instance, none last year but some the year before.

      1. kevan hubbard

        You get good pictures of noccullient clouds often from places like Estonia I think Tallinn must be pushing 59 north just a tad south of Leningrad/St Petersburg/Petrograd in latitude.heres a non astronomical fact St Petersburg is the most northerly city on Earth with a population of over 1 million and I guess Melbourne the most southern (Melbourne is actually south of Aukland).I usually see them from my mother’s village in north east England at about 54.70 degrees north but only a few times a year in summer,the lower but related nacreous clouds escape me but they’re rare below about 65 north and south.

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