What Happened To The Aurora? / New Forecast For Tonight Sept. 13-14

Observers in Maine were treated to a very nice aurora early last night September 12th. Mike Taylor saw this “intense aurora” light up above the unused railroad tracks along Unity Pond at 8:38 p.m. Click to see more of Mike’s work. Credit: Mike Taylor

Feeling disappointed in the aurora last night? The storm happened as forecast only it petered out just about the time the sky was getting dark across much of North America. Observers in Maine caught a good show early, and the lights even put in an appearance here in northern Minnesota, albeit low in the north from behind clouds.

The Kp index, an indicator of magnetic disturbances in Earth’s magnetosphere, shot up to “7” last night before dropping off to low activity, where it’s remained all day so far today. Credit: NOAA

NOAA space weather forecasters call for minor G1 storm tonight September 13 from about 10 pm to 4 a.m. Central Daylight Time tomorrow.

Minor usually means auroras in the bottom half of the northern sky for skywatchers living in the U.S.-Canada borderland region. You may choose to ignore the forecast and go to bed. I understand. You’re feeling a little burned. Those who feel like soldiering on, remain alert for possible auroras.

ACE orbits ahead of Earth toward the sun and can measure the clouds of plasma belted out by the sun about an hour before they arrive at Earth. Credit: NASA

It’s hard to blame NOAA. Predicting the magnetic inclination of a cloud of solar plasma at a distance is fraught with uncertainty. We get a little help from the Advanced Composition Explorer (ACE) which orbits at the L1 libration point, one of five places near Earth where the sun’s and Earth’s gravity are in balance, allowing a satellite placed there to remain relatively stationary. ACE pivots about some 932,000 miles (1.5 million km) from Earth and 92 million miles (148.5 million km) from the sun.

The probe detects the direction, strength and magnetic field particulars of incoming blasts of particles from the sun and provides advance warning of about one hour of dangerous storms. Storms that affect power grids, satellites and of course paint the sky in northern lights. It also measures the magnetic properties of the cloud and relays that data in real time for us to see in the ACE plots.

ACE plot of magnetic field direction or Bz from last night. You can see how the storm dissipated once the magnetic direction of the cloud changed from south (during the storm) to north (above the white horizontal line). Credit: NASA

Yesterday’s big puff of electrons and protons came packaged in a magnetic field that linked into Earth’s  – at first. But later in the evening, the cloud’s magnetic field changed from south to north and was effectively cut off from connecting with our planet’s magnetic bubble. Earth gave it the cold shoulder, and you and I lost some sleep.

After tonight, calmer conditions are expected for a couple days. After that, it’s anyone’s guess. I’ll be watching tonight and report back.

20 Responses

  1. Edward O'Reilly

    Hi Bob.The New Brunswick,Canada experience was similar to what was seen in Maine.The aurora switched on between 9:45 and 10:10 PM local time.There were lovely spikes and shafts of greenish white light emanating up from the northern horizon,reaching to an altitude of roughly 45 degrees.There was also a hint of red discernible to the naked eye.Camera shots of 45 seconds or greater brought out stunning beauty-some of the shots even more vivid than the one from Maine that you posted.And the whole display was in and out in 25 minutes!

  2. Lois Pauluk

    I feel like I will NEVER see the northern lights. I live in Minneapolis, MN and have never seen them. I used to camp up north, too. Never ever good timing. Where and when can I see them. It’s on my bucket list. I am 57.

    1. Tim French

      Hey, Lois. Hang in there. My wife and I live in the state of Virginia. We moved to the Iron Range of Minnesota from 2003 to 2006 and we must have seen the Northern Lights 50 or 60 times in 3 years. I think that was during a solar maximum, though. Also, the really good light show (overhead flowing like a river in the sky) I actually only saw 3 or 5 times. More often than not, the lights would be a greenish/whitish glow on the northern horizon. The important thing seemed to be to get away from the city and be in a location where there are no cities to your north. Then when you see a glow on the horizon in a minor light show, you know you are seeing the aurora… and not just the distant glow of a city. Spend more time north of Duluth… and you will see them! I promise. -Tim

    1. astrobob

      I agree – that’s puzzling, although Bz was at +20 for several hours AFTER the aurora died back following the dip to -20 during the storm. The auroral oval plots also don’t always correspond to what you see. I’ve noticed this a few times when the aurora is visible in Duluth, but POES shows it pulled back too far to see. I’ll call my contact at NOAA to see if I can get some clarification. Will get back to you. Thanks!

    2. astrobob

      If you’re still out there, I talked with the lead NOAA space weather forecaster today. He said that although there was and can be some activity when the Bz goes north, the lion’s share of the auroral activity that night was from the south Bz. He added that it’s not always best to go by the POES diagrams – Ovation is better.

  3. Edward O'Reilly

    It was lovely but surprisingly brief.Have never seen an aurora turn on(like flipping a switch)-and then turn off-so quickly.It was a lovely- but very odd-display

  4. Emily Gordon

    Saw something , I’m guessing a meteorite , I saw the beginning part and my friend saw the end part of the quick but awesome show. What I saw looked initially like a shooting star but then it became a huge long tail that was blue and yellow. My friend saw the last part of it , I was so excited that I missed it because I was telling my friend and she turned around and saw What she described as a shooting star falling VERY close to earth and then from what looked only about 20 yards above earth it looked like a firecracker fizzling out. This was sept 18, 2014 at approx. 10:50 p.m. mountain standard time in northwest Weld County, Colorado.

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