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.

Showtime! Aurora makes first appearance – updated

A diffuse double is seen low in the northern sky at 9:30 p.m. CDT this evening September 11, 2014. The Big Dipper is off to the left. Credit: Bob King

(Scroll down for the latest update)

Just came in from a check on the northern lights and they’re out. Just a quiet start, but I can see a classic green arc low in the northern sky. Once my eyes were dark adapted, faint rays streaked the sky above the arc. No doubt they would have stood out more boldly were it not for the rising gibbous moon off to the east. Stay tuned for more updates during the night.

Faint rays streak either side of this photo taken at 9:35 p.m. Moonlight lowered the contrast but they were dimly visible with the naked eye. Credit: Bob King

Here are some links for you to check out to help you plan through the night:

The approximate extent of the auroral oval forecast for 10:30 p.m. CDT from Ovation. Credit: NOAA

* Ovation oval – shows the approximate extent of the auroral oval that looks like a cap centered on Earth’s geomagnetic pole. During storms, the oval extends south into the northern U.S. and farther.

* Kp index – indicator of magnetic activity high overhead and updated every three hours. A Kp index of “5″ means the onset of a minor storm; a Kp of “6″, a moderate storm.

* NOAA space weather forecast

* Advanced Composition Explorer (ACE) satellite plots - The magnetic field direction of the arriving wind from the sun. The topmost graph, plotting Bz, is your friend. When it drops into the negative zone that’s good! A prolonged stay at -10 or lower increases the chance of seeing the aurora.

* UPDATE 8:15 a.m. Saturday Sept. 13: Well, well, well. Yes, the effects of the solar blast did arrive and we did experience a G3 storm, only the best part happened before nightfall had settled over the U.S. and southern Canada. The peak was also fairly brief. All those arriving protons and electrons connected for a time with Earth’s magnetic field but then disconnected, leaving us with a weak storm for much of the rest of the night. More activity is expected tonight but the forecast calls for a lesser G1 geomagnetic storm.

* UPDATE 10:30 p.m. : Although the aurora has died back, I just got the NOAA forecast update which still calls for a strong storm overnight. Crossing my fingers it happens.

Graph of Bz from the ACE spacecraft shows the past 24 hours of solar wind direction changes. Far right is 11 p.m. CDT Credit: NOAA

* UPDATE 9:30 p.m. : Definite aurora seen through breaks in the clouds low in the northern sky here in Duluth, Minn. After a big surge late this afternoon and during early evening, activity’s temporarily dropped off. The ACE plot has “gone north”. Will keep tabs and report back.

UPDATE Friday 7:30 p.m September 12: Wow! Kp=7 (G3 storm). Auroras should be visible now over the far eastern seaboard of Canada including New Brunswick and the Gaspe Peninsula. If I were a betting man, folks in Maine should see at least a low, glowing arc in the northern sky. Still dusk here in Duluth.

UPDATE Friday 3 p.m.: The Kp index is now at “5″ or minor storm. If you live in the Scandinavian countries or Iceland, you’re getting a very good show right now.

* UPDATE Friday 9 a.m. September 12: Auroras did appear as forecast overnight beginning at nightfall and continuing through about 1 a.m. this morning. Then the action stopped. The Kp index reached “5″ during that time leading to a G1 or minor geomagnetic storm. It wasn’t a particularly bright aurora, remained low in the northern sky and had to compete with moonlight, so many of you may not have seen it.

The stronger G3 geomagnetic storm from the second and more Earth-directed solar blast is still forecast for tonight. This should bring a much better display and should begin right at nightfall. Peak is expected between 10 p.m. and 1 a.m. Central Daylight Time.

My forecast is good, so I’ll be updating during the night. Good luck and clear skies!

Quiet aurora tonight Aug. 27-28

A lquiet auroral arc topped by a faint pink band glowed softly in the northern sky tonight at 10:30 p.m.. The bright star at right is Capella in the constellation Auriga. Credit: Bob King

After Wednesday morning’s fine display, the current wave of magnetic activity is subsiding but not without leaving a tasty leftover. A low, quiet arc has hovered over the northern horizon all evening. Maybe it will take off again as the aurora did this morning, but the forecast indicates a gradual decline in activity overnight.

Map showing the extent of the auroral oval early this Thursday morning August 28. The arc in the photo above is the edge of the large, permanent oval of aurora centered on Earth’s geomagnetic pole. In this map, which is based on satellite data, you can see that the edge of the oval lies right at Minnesota’s northern border. Click to see the current oval. Credit: NOAA

If you live in in the northern U.S. away from city lights and enjoy the subtle side of nature, you’ll find tonight’s aurora suitable for contemplation.

Beautiful rays of aurora dapple the dawn sky

At 4:45 a.m. CDT this morning (Aug. 27) spectacular rays erupted from a low, bright green arc and paraded across the northern sky. Credit: Bob King

Maybe it’s because of the name aurora, which means ‘dawn’, but that’s exactly when the northern lights put on one great show this morning. With clouds constantly a bother this late summer, many of us have been thwarted in viewing all manner of conjunctions, comets and moonrises. Not this morning. I was determined to see Comet Oukaimeden near Orion just before dawn. And that’s exactly how I happened to be up to catch a surprisingly fine aurora.

A striking green arc perforated by many needle-like rays. Credit: Bob King

One of the keys to maximizing enjoyment of the aurora is to have a place you can get to with a low northern horizon. At least from mid-northern latitudes, lots of activity often occurs very low in the northern sky.

High speed electrons from the sun spiral down individual magnetic field lines in Earth’s magnetic bubble called the magnetosphere to create multiple parallel rays when they strike oxygen and nitrogen atoms in the upper atmosphere. Credit: Bob King

We were already primed for northern lights because of the NOAA space weather forecast, so when I looked out the window at 4 a.m., there they were.

I jumped in the car and sped to a country road not far from home. Arriving around 4:30 a.m. several pale green arcs snaked across the north, and within minutes they erupted with massive parallel rays. To the eye, the tall rays were colorless, but they loved the time exposure afforded them by the camera.

The pictures were taken using a 17mm lens at f/2.8, ISO 800 and exposure times around 15 seconds.

While I did get to see my comet in the nick of time, the northern lights made it more than worth my while. I hope you got to see them, too.

Jupiter (lower left next to the star Delta in Cancer) and Orion (upper right) sparkle in the dawn sky over Duluth, Minn. Wednesday morning. Credit: Bob King

The display continued deep into twilight and no doubt carried into darker skies farther west of my location. There’s still a possibility for minor auroras early tonight. I hope so. Two 4 a.m. stints in a row would kill me.

Surprising aurora puts on great show last night

Auroral arcs are topped by red rays light up the northeast while the moon (0verexposed) and Jupiter shine off to the west in this photo taken last night over a small lake north of Duluth, Minn. Both moon and aurora light are reflected in puddles on the ice. Credit: Bob King

No, it wasn’t in the forecast but just the like real weather, the unexpected happens. A change in the “magnetic direction” of the wind of particles from the sun called the solar wind from north to south made all the difference. Earth’s magnetic field points northward. When the field associated with a batch of plasma from the sun points southward, as it did beginning early yesterday evening, there’s a good chance it will link into our field and ultimately allow those particles passage into our upper atmosphere.

A large red patch briefly glowed above the bright green arc around 11:15 p.m. last night May 3. The color was dimly visible with the naked eye. Credit: Bob King

Spiraling down magnetic field lines like firefighters on a firepoles, billions of tiny solar electrons strike oxygen and nitrogen molecules in the thin air 60-125 miles up. When the excited atoms return back to their normal rest states, they shoot off niblets of green and red light that wash the sky in multicolor arcs and rays.

The whole northern sky lit up with green and red rays earlier this morning. While the green color was easy to see, the red was very pale. The human eye is much more sensitive to green light than red, one of the reasons why the aurora rarely appears red except in a camera during a time exposure. Credit: Bob King

Nothing in the space weather forecast would have led you to believe northern lights were in the offing for mid-latitude skywatchers last night. Maybe a small possibility of a glow very low on the northern horizon. Maybe. Instead we got the full-blown show with auroras of many forms jumping, glowing and dancing all night long. When I finally hit the hay at 4 a.m. flames of moderately bright aurora still rippled across the north.

So what about tonight? Just like last night, there’s only a 5% chance of a minor storm. Like I always say, take a look anyway, because nature always has a surprise or two up her sleeve.

Aurora out tonight May 3-4 over northern U.S.

There may be a lot of trees in this view but they don’t hide the fact that the northern lights are visible tonight right now (10:30 p.m. May 3) low in the northern sky. Take a look if it’s clear by you. Credit: Bob King

(UPDATE May 4: Click HERE to see what a fine show the aurora gave us overnight.)

Watch for auroras tonight. 15 minutes ago, a bright arc lit up in the northern sky here in Duluth, Minn. No way to know if it will fade or go wild, so be sure to take a look if it’s clear tonight. The magnetic field in the solar wind tipped southward this evening, weaseling a connection to Earth’s own magnetic domain and sparking a small display of northern lights. I’m headed back out for more. Good luck – let’s hope it continues.

Chance again tonight April 20-21 for northern lights

Very nice aurora north of Duluth about 10 p.m. Sunday night. The rays were intensely colorful in the camera but much paler to the eye. Credit: Bob King

There’s been some action on the aurora scene today. A coronal mass ejection from the sun blew by Earth this afternoon and sparked auroras over northern Scandinavia and other locations in northern Europe where it was dark at the time. There’s continues to be a fair chance for minor auroras over the northern U.S. tonight (Sun. April 20-21), so you may want to be on the lookout. Check the Ovation Aurora site to see the extent of the aurora in near real time.

Curious crossing of colors – tall pink rays in front of a low green arc.  Amazing! Credit: Bob King

UPDATE 1 a.m. April 21 — The northern lights made a decent showing over northern Minnesota between the end of twilight around 9:30 p.m. until about 10:45 p.m. Sunday night. Lots of slow-moving, “lazy” rays to 50 degrees across the north. Extremely colorful in the camera but pale pink-purple to the naked eye at best. Hope you got to see the show.

Occasional rays formed that glowed for many seconds at a time before fading away appeared in the northern sky. Credit: Bob King

Northern lights alert Feb. 18-19 – They’re out there!

A complete surprise. I was out with my astronomy class this evening and the northern lights suddenly showed around 8:30 p.m. Sure wish I’d brought a tripod. This photo taken on a monopod. Credit: Bob King

It wasn’t in the forecast but then sometimes the best things aren’t. Let’s just say the aurora is cooking away very nicely across the northern sky with rays to 40 degrees high as of 10 p.m. Some nice curtains near the horizon and even color. I’ve seen obvious pink tops on some of the taller, brighter rays.

The aurora died back around 9:30 p.m. but surged again after 10 o’clock. This photo was taken at 10:30 p.m. CST. when much of the northern sky showed good activity. Credit: Bob King

Even though the waning gibbous moon is up, if you have a chance, check out the northern sky. Moonlight lowers the contrast of the display some, but once your eyes are dark-adapted, there was lots to see (at least from 8:30-10:30 p.m.). Hopefully the display will continue long into the night.

Aurora in the northeastern sky around 10:15 p.m. tonight Feb. 18, 2014. Credit: Bob King

An unexpected passage of a high-speed solar wind gust that happened to be pointing in the right magnetic direction (south Bz) hooked into Earth’s protective magnetic field and sparked the display. The Kp index, which slumbered all day in the low activity, green zone shot up into the red at Kp=5 during the early evening.

You can stay in touch with what the aurora’s doing overnight by clicking on the Kp link above as well as the Ovation auroral oval site which shows the extent of the aurora.

Good luck in your viewing!

Extent of the aurora oval around midnight CST Feb. 18-19. The map, based on satellite data, indicates that aurora should be visible at least across the northern tier states. Credit: NOAA

UPDATE 11:45 p.m. CST: Lots of rays and rayed arcs appearing across the north-northeast up to 45 degrees high. The moon is up higher now reducing contrast but still a fine show.

UPDATE 12:10 a.m. Feb. 19 – Intense, thick green arc slung across the bottom half of the northern sky. Pulses of fainter “flaming” aurora rising to the zenith. Sense that a bright eruption might happen soon.

A singular, colorful auroral ray. Its pink top was obvious with the naked eye. Credit: Bob King

UPDATE Feb. 9 a.m. : The aurora lasted the entire night and peaked around 2-3 a.m. It was still rolling in morning twilight.

Why no aurora last night? Here’s the scoop

Maybe you were expecting something more like this last night? Join the club. Credit: Bob King

Did you plan a vigil the past two nights in hope of seeing the northern lights? I know I did. Lost some sleep over it for sure. As it happened, the display never materialized. Yes, the expected brush with particle blast released by the Jan. 7 solar flare did blow by Earth, but only managed to stir up a nice show in Arctic regions like northern Norway and Finland during afternoon hours for U.S. time zones.

Since auroras in that part of the world are as common as doughnuts, I think we can say this outburst was officially a flop.

I spoke with Joe Kunches, space scientist at the NOAA Space Weather Prediction Center, this morning about the matter. When I first rang, he told me he’d have to call back because the staff was just going into a meeting about this very topic. Hopefully no heads rolled.

Kunches described the solar blast as an empty bottle. “There was nothing in it,” he said. Despite the fact that it made a direct beeline for the planet, there was no way for scientists to know the strength and direction of the magnetic field embedded in the particle cloud.”

The Solar and Heliospheric Observatory (SOHO) monitors the sun from the stable L1 Lagrange Point a million miles sunward of the Earth. The green swirls around the Earth represent its magnetic bubble called the magnetosphere. Credit: NASA/ESA/Steele Hill

“The CME (coronal mass ejection) was slower than the model suggested by 8 hours, which sometimes means that it will be weaker than expected,” said Kunches.

“This illustrates our biggest forecasting challenge,” he went on. “We can see the path but can’t know it contains a strong magnetic field pointing in the right direction by the time it arrives at Earth the way a forecaster knows the barometric pressure of a hurricane.”

What happens to the swirling, whirling cloud of subatomic particles released during a flare must rank a close second to chaos itself. Scientists make detailed observation with dedicated space observatories like SOHO, the Solar Dynamics Observatory and STEREO probes and then model the behavior of the incoming particle winds as best they can:

“Even if they’re right when it leaves the sun, there’s no guarantee it will be that way when it arrives,” said Kunches. CMEs can rotate and deform in unpredictable ways. The key to a solid prediction of auroras very much depends on the direction of the magnetic field within the cloud when it sweeps by Earth, a factor called Bz.

The interplanetary magnetic field, created by a wind of solar plasma entwined with magnetic fields, departs the sun in the shape of a gigantic spiral. As waves of varying strength, density and direction pass by Earth, our planet’s magnetic field occasionally hooks up with the sun’s, making auroras likely. Credit: NASA

Embedded within the sun’s plasma swirls are portions of its magnetic field. As that material – called the interplanetary magnetic field (IMF) – sweeps past Earth, it normally glides by, deflected by our protective magnetic field, and we’re no worse for the wear. But when the solar magnetic field points south – called a southward Bz – it can cancel Earth’s northward-pointing field at the point of contact, opening a portal. Once linked, the IMF dumps its baggage of high-speed particles into our atmosphere to light up the sky with northern lights.

The Jan. 7 solar gust arrived at Earth with a northward pointing Bz. With no coupling, nothing happened. Perhaps you’ve watched the real-time red trace on the ACE satellite’s Bz read-out. For most of the past two days that squiggly line has been “flat as a pancake” as Kunches put it, which did not bode well for auroras. At any time it could have dipped south but never did.

Click to watch a video of the solar wind linking up with Earth’s magnetic field behind the planet, sparking a particle cascade and auroras in our upper atmosphere.

While no method is absolutely guaranteed, I recommend the following sites to check before you get in your car and drive 100 miles to see an aurora:

* ACE Dynamic Plots – The red trace for Bz is the one you’re interested in. If the line dips well below the centerline to -10 or lower, auroras may be likely.
* Ovation Aurora - Simulation of the auroral oval (extent of aurora) based on live satellite data. Pay attention to the location of the red curve showing the southern extent of auroral visibility.
* Kp index – magnetic activity indicator updated every 3 hours. A yellow bar (Kp=4) is a good sign aurora might be visible from the northern U.S. and southern Canada. A red bar (Kp=5 or higher) indicates a larger storm and more extensive aurora.

By the way, Kunches says that the CME has blown by and doesn’t expect any northern lights for tonight, so catch up on your sleep. In the meantime, put on your philosophical cap and reflect about how much we really don’t know about the world. Always a great motivation to learn more.

Aurora Alert! – Good chance for northern lights tonight and tomorrow Jan. 8-9

A bright curtain of aurora drapes the northern sky two summers ago. Credit: Bob King

It’s not often you see “major” and “severe” geomagnetic storms in the space weather forecast, but here it is:

“Quiet to severe storm levels on day one (9 Jan.), unsettled to severe storm levels on day two (10 Jan.) …”

These dates are Greenwich time so Jan. 9 means sometime overnight tonight (Jan. 8-9) for U.S. and Canadian time zones. All this excitement is brought to you by the current huge sunspot group known as Active Region 1944, which contains one of the biggest sunspots seen in years.

Big sunspot group 1944 at 4:45 p.m. CST today. Credit: NASA

The entire works spans some 125,000 miles (200,000 km) or more than 15 times the size of the Earth. It’s spawned multiple M-class (moderate) flares and at least one X-class (strong) flare in the past couple days, sending high-speed streams of protons and electrons in Earth’s direction.

There’s an 80% chance of additional M-class and 50% chance of X-class flare from this very active group in the coming days. Sunspot groups are regions on the sun’s surface where magnetic energy is strongly concentrated like a giant bar magnet with north and south poles. In simple groups, the positive and negative magnetic poles are separated from one another and not likely to come in contact and cause trouble. Astronomers say these groups have a “beta” magnetic classification.

The X1-class flare that popped off earlier yesterday Jan. 7 in the big sunspot group cut loose a large, high-speed cloud of particles called a coronal mass ejection. Some of that material will start arriving in Earth’s vicinity late tonight. Click to see animation. This photo was taken with the SOHO coronagraph. Credit: NASA/ESA

Huge complicated groups like 1944 have a beta-gamma-delta magnetic field where spots of opposite polarities lie near one another with no clear division between them. This is where things get volatile. The more complicated a sunspot group’s magnetic field becomes, the greater the potential for magnetic mischief. Opposite polarities can interact in the churnin’, burnin’ solar soup and spawn strong flares.

When those speedy particles arrive and hook in to Earth’s magnetic field, which we dearly hope will happen, they spiral toward our magnetic poles, crashing into air molecules and exciting them to fluoresce as northern lights.

Let’s hope that transpires either tonight or tomorrow night. The moon – now just over half – won’t be enough to wash out the sky like a full moon would, and it sets just after 1 a.m., leaving a completely dark sky. Cross your fingers and get ready – the sky may go electric tonight. It’s clear here in Duluth, Minn., so I’ll be monitoring and updating.

UPDATE: 9:30 a.m. CST today: Expected northern lights didn’t happen overnight. Nothing seen from Duluth, Minn.. Chances are even better for auroras to break out tonight, so don’t give up the vigil. I’ll update later today.