Aurora alert tonight Aug. 26-27 – updated

Painting by Etienne Trouvelot of a spectacular aurora observed on March 1, 1872.

North Americans skywatchers missed the last week’s aurora by the skin of our teeth. By nightfall, the whole display, enjoyed earlier from Scandinavia, went to heck. Maybe tonight will be different.

For the past few days NOAA space weather forecasters have been predicting a minor geomagnetic storm (Kp = 5) from incoming blasts of solar particles called coronal mass ejections that departed the sun on Aug. 22. ‘Minor’ often translates to an auroral arc (sometimes two) low in the northern sky pierced by occasional rays.

No great shakes, but if you live in the northern U.S. and southern Canada, be aware you might be visited by the green ghost. Activity should commence after sunset and peak between 1-4 a.m. CDT tomorrow morning Aug. 27.

Maybe we’ll get burned again. But you wouldn’t want me to keep this all to myself, would you?

* UPDATE 5:30 a.m. CDT: Big auroras lit up the northern sky this morning. Lots of arcs and long rays seen from Duluth, Minn. If you live in the northern third of the U.S. and it’s still dark, go out for a look.

Aurora alert tonight Aug. 2 / Rosetta comet update – striking new details!

A CME or coronal mass ejection erupting on July 30 may lead to a small display of northern lights tonight. Jupiter at right in this photo made with the coronagraph on the Solar and Heliospheric Observatory. Credit: NASA/ESA

Minor auroras might visit skies across the northern U.S. and southern Canada tonight, the result of a coronal mass ejection from an erupting filament on July 30. Filaments are clouds of hot hydrogen gas suspended in the sun’s lower atmosphere. They often stay put for days, but a little magnetic instability can launch one into space.

Material from the filament is expected to begin arriving this afternoon and continue into the evening hours. I’ll have an update later if auroras materialize. Meanwhile, keep an eye on the northern horizon when it gets dark tonight. Fortunately, the moon will only be a half and not wash out the sky.

Comet 67P/Churyumov-Gerasimenko at 621 miles (1,000 km) on August 1. Wow! Look at that richly-textured surface. This photo has higher resolution than previous images because it was taken with Rosetta’s narrow angle camera. The black spot is an artifact. Credit: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA

Rosetta sent two new pictures of Comet 67P/C-G from 621 miles (1,000 km) away that show striking new details including new artifacts. I’ve done some digging around and discovered that the dome-like features and ‘craters’ seen on the past couple photos are really artifacts due to image processing.

Wider-angle and lower resolution navigation camera photo of the comet. More artifacts are seen including what look like bumps or boulders. Credit: ESA

You’ll see a black spot (artifact) in the narrow-angle camera and another dome artifact in the Navcam photo. They’re generally pairs of bad pixels that get smoothed out in processing to look like real features on the comet’s surface. Those should go away once the spacecraft is close enough for the comet to fill the field of view.

Polka dots and sunbeams a solar observer’s dream

Sunspots speckle the sun like polka dots in this photo taken early this morning by NASA’s Solar Dynamics Telescope (SDO). The largest spot (right of center) belongs to sunspot group 2055. The view is very similar to that seen through a typical amateur telescope equipped with a safe solar filter. Sunspots are regions where magnetic energy is concentrated on the sun’s surface. Credit: NASA

For a change it was wonderful to show people a heavily speckled sun at Astronomy Day festivities yesterday. If it’s clear – rare enough in itself – sunspots are usually little more than crumb-sized and look like flecks of dirt or dust through the eyepiece.

Kids and adults eager to see sunspots queue up at Jim Schaff’s dual telescopes, which showed the sun in both visible light and deep red hydrogen-alpha. Schaff, of Duluth, is at left. Credit: Bob King

But this week the past few days, the sun’s been showing off a half dozen spots as large or larger than the planet you toil upon. There are currently at least 8 numbered sunspot groups. One of them, the leader spot in group 2055, was easily seen through a #14 welder’s glass this morning.

A C4-class flare in sunspot region 2055 early yesterday evening May 10 glares in this photo made in ultraviolet light by SDO. More flares up to M-class are possible from this region in the coming days. Credit: NASA

To be visible with the naked eye (with filter), a sunspot or sunspot group has to extend some 31,000 miles (50,000 km) or about 4 times the diameter of Earth. While enormous, about 2-3% of sunspots and sunspot groups or about 100 per 11-year solar cycle can be seen by a dedicated solar observer, proving you don’t need a telescope to follow the general trend of the 11-year sunspot cycle.

The first drawing of sunspots was made by English monk John of Worcester in 1128 A.D.

The first written records of sunspots come to us from the Chinese as long ago as 800 B.C. Court astrologers in China and Korea kept tracks of spots because they believed they foretold important events. The earliest known drawing of sunspots was made almost 500 years before the invention of the telescope by English monk and chronicler John of Worchester. On Dec. 8. 1128 A.D., Brother John wrote:

“…from morning to evening, appeared something like two black circles within the disk of the Sun, the one in the upper part being bigger, the other in the lower part smaller. As shown on the drawing.”

First photo of the sun using the daguerrotype process taken by Fizeau and Foucault on April 2, 1845. Though fuzzy, you can still make out sunspot groups and the basic dark umbra-lighter penumbra structure of the spots. Credit: ESA

His sighting was followed five days later by a red aurora recorded over Korea. The two may have been related.

As long as we’re talking firsts, the first successful photograph of the sun and sunspots was made on April 2, 1845 by French physicists Louis Fizeau and Leon Foucault on daguerrotype with an exposure of 1/60 of a second. It looks pretty rough but photography only improved from there.

Nowadays, anyone with a safe solar filter for either naked eye or telescope use can see what the sun’s up to. Solar telescopes in orbit and on the ground photograph the sun almost continuously. NASA’s dual STEREO orbiting solar probes even show us what’s happening the side facing away from Earth.

A prominence eruption blasted a CME or coronal mass ejection off the northeast side of the sun very early this morning. It’s not Earth-directed. This photo was taken by the Solar and Heliospheric Observatory (SOHO) which uses a disk to block direct sunlight. Credit: NASA/ESA

We not only want to learn more about how the sun works, but we’re justifiably concerned about its storms and how they affect our planet.

Strong solar flare creates rare magnetic ripples in Earth’s atmosphere

Energy stored in twisted magnetic fields above sunspot group 2017 was released a as a strong X1-class flare at 12:52 p.m. CDT March 29. Powerful X-rays from the flare sent magnetic currents through Earth’s upper atmosphere minutes later. Credit: NASA

An fast, intense X1-class solar flare yesterday afternoon not only blasted a cloud of solar electrons and protons into space but also sent magnetic ripples across Earth’s upper atmosphere creating what astronomers call a magnetic crochet.


X1 solar flare on March 29, 2014

Normally it takes an average of 4 days for a cloud of fast moving solar particles called a coronal mass ejection or CME to reach the Earth. Fast ones moving at 620 miles per second (1,000 km/sec) arrive in about 42 hours. But energy levels rose so rapidly in yesterday’s flare that Earth’s atmosphere was affected only minutes after the onset of the storm.

How could something from the sun get here so fast? Well, it does everyday. Sunlight traverses the 93 million miles between Earth and sun in just 8.3 minutes. There are many forms of light from radio waves to visible light to X-rays. Flares are so powerful they kick out waves of light energy across the entire spectrum from radio to deadly gamma rays.

The Earth’s ionosphere, divided into layers D, E and F, begins about 37 miles high and extends nearly to space. Solar and cosmic radiation strips electrons from atoms turning them into ions, which respond to electrical and magnetic fields. Credit: Rutherford Appleton Laboratory

A burst of X-rays from sunspot region 2017 arrived 8.3 minutes after the blast and increased the electrical conductivity in the D and E layers of Earth’s ionosphere by stripping electrons from the atoms there, making electric currents flow more easily. Because moving electrical currents create magnetic fields, the flare caused a sudden jump or ripple of magnetic energy to pulse through the ionosphere. As the flare subsided, those layers returned to normal.

You can see for yourself how an electric current creates a magnetic field by holding a compass near an operating electric shaver or hairdryer. As you move the shaver back and forth, the compass needle will swing wildly as it responds to the local magnetic field created by the flow of electrons in the current.

Even though we can’t see them, magnetic fields have very real effects.

Magnetic crochets are rare because they only occur during large flares that peak quickly. They’re also typically recorded at locations where the sun is overhead at the time of the flare.

Just one more way the sun touches our lives. As for the particles propelled by the flare, most of them took off northward of Earth but a glancing blow is expected around April 1 when Arctic observers may see a nice show of northern lights during their rapidly diminishing nighttime hours.

Big sunspot livens up a quiet sun / Chance for auroras overnight Feb. 1-2

Sunspot region 1967 dominates the solar disk in this photo made late Jan. 31 by the Solar Dynamics Observatory. Credit: NASA

Sunspot group 1967 burst onto the scene on Jan. 28. Now it’s big enough to easily see with the naked eye through a safe solar filter. The group’s twisty, complex magnetic field has already ignited a significant M6 flare on the 30th with a 60% chance for more M-class flares in the next three days.

The expanding cloud of solar plasma called a coronal mass ejection caught blasting away from sunspot group 1967 on Jan. 30 photographed by the Solar Heliospheric Observatory. Credit: NASA/ESA

The Jan. 30 event kicked out a high-speed proton-electron soup called a coronal mass ejection, a part of which will graze Earth overnight tonight (Feb. 1-2) and may spark a northern light display at high latitudes. Of course there’s always a chance southern Canada and the northern border states of the U.S. will see some action, too.

Since there’s been such a dearth of auroras of late, I wanted to share this bit of potentially good news. I’ll post updates if the lights make an appearance.

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.

Chance for auroras across northern U.S. tonight Oct. 8-9

A coronal mass ejection of CME was photographed by the STEREO Behind probe, which looks at the back of the sun not visible from Earth, during early afternoon Oct. 6. The telescope uses a special instrument called a coronagraph to block the solar glare. Click for a short video of the blast. Credit: NASA

An interplanetary shock wave possibly associated with an Oct. 6 coronal mass ejection (CME) blew by Earth this afternoon and sparked auroras at high latitudes. As of 6 p.m. CDT we’re in the middle of a minor G1 geomagnetic storm. Judging from the satellite images of the auroral oval, the “apron” of northern lights that spreads outward across the polar regions, skywatchers across much of Scandinavia are getting a good show.

UPDATE: The aurora is out right now (8 p.m. CDT) here in Duluth, Minn. I’ve also heard of another report of northern lights over Maine.

Dim but active aurora drapes the northern sky to 45 degrees altitude at 7:50 p.m. this evening. Credit: Bob King

Observers in the northern U.S. and southern Canada should be on the lookout for possible auroras this evening. NOAA forecasters are calling for a 25 percent chance of minor storms at mid-latitudes. Here in northern Minnesota, we’re at 100 percent; aurora now fills half the northern sky. Nothing dramatic just yet – lots of faint rays and an occasional band or two.

A plot of the aurora oval in the northern hemisphere made with the POES satellite at 7:45 p.m. CDT shows it expanding southward over Scandinavia and Canada. When activity is low, the oval shrinks to a small circle in the far north. As more particles stream in from the sun, the oval expands southward. Credit: NOAA

Just a quick note on the photo at very top. It was taken by the STEREO Behind spacecraft and provides a perspective on the sun impossible with ground-based telescopes. STEREO-B trails far behind the Earth as it orbits the sun, keeping an eye on the solar backside. A second STEREO Ahead probe monitors the Earth-facing hemisphere for complete sun coverage.

Good luck tonight!

Aurora alert tonight May 17-18, 2013

This map created with satellite data for 11:30 p.m. CDT May 17 shows the extent of the northern auroral oval, one of two permanent caps of aurora centered on Earth’s north and south geomagnetic poles. Normally the oval is small and snugged up over Hudson Bay. Tonight it’s expanded southward and could produce auroras across the northern border of the U.S. Click to see current oval. Credit: NOAA

If it were clear here in Duluth, I’m sure we’d be seeing northern lights. The Kp index, an indicator of magnetic activity around the Earth, shot up to “5″ or minor storm level around 11 p.m. Central time this evening (Friday). From the satellite plot, it appears the auroral oval extends across southern Canada almost to the U.S. border.

Since the aurora is quite high – around 60-200 miles – it’s visible a fair distance to the south of that line. In other words, northern parts of Minnesota, Michigan, Wisconsin, N. Dakota, Montana and Washington may get treated to the sight of northern lights overnight.

Sunspot region 1748 still has the potential for more solar storms. Since the group’s now becoming more face-on to Earth, additional flares could send CMEs in our direction. Another flare on May 17 sent material expected to arrive on the 19th. Credit: NASA

Be sure to take a look at the northern sky tonight for arcs and rays of aurora. As you might guess, the cause for this show lies with the recent X-class flares sunspot region 1748 has been pounding out over the week. Our planet was expected to get a glancing brush from a coronal mass ejection (CME) overnight from one of the recent blasts. Let us know if you see anything. And get ready for May 19 – Sunday – when another blast could spark an even more auroras.

Lizard Lemmon Comet loses tail, grows a new one

Comet C/2012 F6 Lemmon photographed on May 15 showing its bluish, ion tail (bottom) beginning to peel away from the comet. The dust tail sticks out to the left. A wispy, new gas tail is already growing above the departing one. Credit: Damian Peach

Solar winds snapped off Comet Lemmon’s ponytail this week and sent it reeling into space. Not to worry. Comets possess the remarkable ability, shared by many species of lizards, to grow new ones. A lizard loses its tail to distract and escape a predator; a comet because its charged atoms – called ions – interact with the breezy blasts of charged particles from the sun called the solar wind.

Magnetic fields in the solar wind tore off Comet Lulin’s tail on Feb. 4, 2007. You can clearly see it falling away in the bottom frame. Credit: Joseph Brimacombe

One day Comet Lemmon was minding its own business and then on Wednesday morning, one of its two tails underwent a “disconnection event”. Comets frequently grow two tails when they orbit near the sun – a pale yellow one of fine dust and a blue one of ionized (electrically charged) gas. The blue color comes from ionized carbon monoxide which fluoresces blue when excited by ultraviolet light from the sun. The larger particles in a comet’s dust tail have no electric charge and aren’t affected by the solar wind; they get pushed away from the comet’s head by the pressure of sunlight.

Charged particles from the sun – electrons and protons – plow through the solar system and continuously interact with comets creating picturesque kinks and ripples in their ion tails. Wrapped up into this electrical mix are solar magnetic fields with north and south-directly poles similar to those on a horseshoe magnet.

 

Invisible magnetic field lines are made visible around a bar magnet when you sprinkle iron filings around it. The sun’s wind likewise has lines of magnetic force embedded within it created by moving charged (electric) particles.

Electricity and magnetism go hand in hand. A spinning magnet creates an electrical field and an electric current creates a magnetic field. Every time you turn on a lamp, the wires inside the cord are looped by invisible but very real magnetic fields.

Solar flare eruptions like the powerful X-class flares earlier this week can direct huge clouds of magnetized (and electrified) clouds of gas called coronal mass ejections or CMEs into space. When one smacks into a comet, it can rip its tail right off.

Magnetic field lines bound up in the sun’s wind pile up and drape around a comet’s nucleus to shape the blue ion tail. Notice the oppositely-directed fields on the comet’s backside. The top set points away from the comet; the bottom set toward. In strong wind gusts, the two can be squeezed together and reconnect, releasing energy that snaps off a comet’s tail. Credit: Tufts University

Comets present obstacles to the solar wind. The magnetic field carried by the sun’s constant wind gets pushed back by the comet’s electrified gases causing it to drape and flow around the comet’s head. That’s what forms the streamlined blue ion tail in the first place. But when an especially powerful blast of wind blows by, it can elbow its way around the backside of the comet and reconnect with itself, releasing a burst of energy that snaps off the tail.

Diagram showing how a CME slams into a comet (B) to create a tail disconnection event, known in the biz as a DE. Soon enough the comet grows a new one (D). Credit: NASA

In a very real sense, Comet Lemmon experienced a space weather event much like what happens when a powerful solar wind reconnects streams around Earth’s magnetic field and reconnects on the back or nightside of the planet. The energy released sends zillions of electrons and protons screaming down into our upper atmosphere where they stimulate the air molecules to produce auroras. One wonders whether comets might even have their own brief displays of northern lights.

As the solar wind flows away from the Sun, it creates a spiral-shaped interplanetary magnetic field (IMF). Two to four sectors – where the field is pointed toward or away from the sun – spin out every solar rotation (27 days). Each sector Credit: NASA

It’s unclear what pinched Lemmon’s tail since all four large flares from sunspot group 1748 and their associated CMEs weren’t directed at Comet Lemmon.

Maybe the comet crossed a sector boundary where the magnetic field carried across the solar system by sun’s steady breeze changed direction from south to north or north to south. When it sped across the older field wrapped around Lemmon, the two once may have linked up in a burst of energy.

When a lizard loses its tail, it may gain its life, but still suffer for the trouble. For a time, its sense of balance is compromised and important fat reserves stored in the tail aren’t available. Comet Lemmon will be no worse for the wear. As soon as the old tail drifts away, a new one sprouts in its place, cooked up by the ever-steady sun.

Read more about tail disconnections HERE; check out a map for finding Comet Lemmon HERE.

A 3rd X-class flare rocks the sun

The latest X3.2 flare in far ultraviolet light at 8:16 p.m. CDT Monday evening May 13 (May 14 Universal Time) photographed by the Solar Dynamics Observatory. Credit: NASA

Solar activity’s been rising like nobody’s business. Two of the year’s most powerful flares fired off from the sun’s backside late Sunday and at least 8 spot groups speckle the sun’s white-hot surface today.

Another ultraviolet picture of the sun taken by NASA’s STEREO Behind spacecraft late on May 13. The flare looks like a giant spike because the brilliance of the explosion saturated the camera sensors. STEREO Behind orbits well behind Earth and sees a part of the sun’s backside not visible with Earth-based telescopes. Click to learn more about the STEREO probes. Credit: NASA

Now we can add a third strong X-ray class flare, an X3.2 that spewed a vast cloud of high-speed solar gases called a coronal mass ejection (CME). Lucky for Earth, it was directed – as the other flares were – away from our planet off the eastern edge of the sun’s disk.

The most energetic flare measured in the modern era occurred on November 4, 2003 during the last solar maximum. No one knows how truly strong it became since the sensors topped out at X28. But any flare in the X-category can affect everything from GPS satellites to radio communications, satellite electronics and even fry poorly-protected power grids.

The sun in normal white light late Monday with sunspot groups labeled. Region 1748 – site of the strong flares of the past few days –  is just coming into view at far left. Credit: NASA

Solar flares typically occur in sunspot groups where magnetic energy is concentrated. The  solar surface, which bubbles and churns like a monster pot of hot oatmeal, brings opposite magnetic fields (north and south poles) in contact with one another. When they reconnect, the sudden release of energy heats solar gases to many millions of degrees and blasts billions of solar electrons and protons into space as a CME.

The amount of energy from a big flare like the ones we’ve seen recently equals millions of thermonuclear (hydrogen) bombs.

A healthy CME (coronal mass ejection) in the wake of the most recent X3.2 flare late Monday. This photo was taken by the Solar and Heliospheric Observatory which uses a special mask to block out the bright sun to better photograph it outer atmosphere. Credit: NASA / ESA

The sunspot group responsible for all the current feistiness goes by the name of 1748; it’s just coming around to the sun’s front side. Though highly foreshortened because we’re peering at it along the extreme edge of the sun, you can tell it’s a big one. Let’s hope it kicks and sputters its way to a northern lights display without any serious damage to our favorite toys.