Shhh! Don’t wake the sun

Contrast these views of the nearly spotless sun on July 16-17, 2014 with a picture taken about two weeks earlier (below). Credit: Giorgio Rizzarelli

Who doesn’t enjoy a nap on a lazy summer afternoon? That’s what the sun’s been up to past few days. Instead of a steady parade of sunspots, it put its pencils away and went to sleep. For a time on July 17 not a singe magnetic blemish marred the entire Earth-facing hemisphere. The last time that happened was nearly 3 years ago on Aug. 14, 2011.

Ten groups including three visible with the naked eye dot the sun on July 8, 2014. Credit: NASA

The solar blank stare lasted but a day; by the 18th two small groups emerged. Today three little spot clusters have emerged but again, they’re on the small side.

I think the reason the sun looks so stark is that only two weeks ago nearly a dozen sunspot regions freckled the disk including three visible with the naked eye with a safe solar filter.

These ups and downs aren’t unusual unless this downturn continues for weeks. Expect more bubbles of magnetic energy to rise from beneath the glaring surface of the sun called the photosphere and spawn fresh groups soon. Because we now have eyes on the farside of the sun courtesy of the dual STEREO solar probes, we know the complete story. There are at least seven spotted regions in hiding there today.

Sunspot numbers are plotted for the last three solar cycles through the present. The double peak of the current cycle is shown. Credit: NASA

Sunspots and flares peak approximately every 11 years. We’re still riding the roller coaster near the top of the arc after the most recent solar maximum in late 2013. Some maxima are strong, others weak. The current max – Cycle 24 – is the weakest since Cycle 14 in February of 1906 and one of the wimpiest on record. Occasionally a cycle will have two peaks like the current one. The first peak occurred in Feb. 2012 and the second just this past June. What makes Cycle 24 even more unusual is that the second peak is higher than the first – the first time this has ever been recorded. Like people, every maximum has a personality of its own.

Doug Bieseker of the NOAA Space Weather Prediction Center has analyzed historical records of solar activity and he finds that most large events such as strong flares and significant geomagnetic storms typically occur in the declining phase of solar cycles—even weak ones, so don’t give up hope for some great auroral displays ahead.

A coronal mass ejection blew off on the farside of the sun early this morning July 20. It appears to envelop Jupiter, but the planet is 490 million miles in the background. SOHO uses an occulting disk to block the brilliant sun. Credit: NASA/ESA

The sun’s got a buddy this week – Jupiter! We can’t see the planet from the ground because it’s swamped by solar glare, but the Solar and Heliospheric Observatory (SOHO) has a great view from space. Watch the sun approach from the right and pass the planet over the next few days. After the 24th, Jupiter will move into the morning sky.

Huge sunspots scar the sun this week

Ten groups including three visible with the naked eye protected with a safe filter dot the sun today. Photo by the Solar Dynamics Observatory (SDO) taken at 8 a.m. CDT today July 9. Credit: NASA

A trio of impressive sunspot groups are parading across the sun’s face this week. Regions 2108, 2109 and 2110 are all closely-spaced and near the center of the disk today. All three require nothing more than a pair of eyes and a safe solar filter to view.

The sun seen through a standard 200mm telephoto lens and solar filter this morning gives you an idea of how the big sunspot groups look to the naked eye. Credit: Bob King

I took a look through my handy #14 welders glass this morning and saw 2110 distinctly; the other two groups blended into a single ‘spot’ at first. Looking closely I could barely split them into two separate dots. The view was spectacular at 30x in my little telescope with a total of ten sunspot groups and lots of fine detail in the three biggest.

Given high sunspot counts, the chance for flaring has been increasing in recent days. Today there’s a 75% chance for moderately strong M-class flares and 20% chance for the most powerful X-class variety.

Safe solar filters come in several varieties of optical / coated plastic and glass. Click to see ones you can purchase from Rainbow Symphony. Credit: Bob King

Curiously, none of the three biggies has shot off a large flare in the past day or two; they’re all currently stable. But the inconspicuous group 2113 fired off a beefy M6 flare only yesterday. It’s not expected to affect Earth, but because 2113 hides a complex magnetic field, future M-class or stronger blasts may be possible.

M6-class solar flare eruption from sunspot group 2113 captured July 8, 2014 at 11:24 a.m. by SDO. Credit: NASA

It seems like we’re due for aurora, so I’d be surprised if the current activity doesn’t lead to at least a minor storm soon. I’ll keep you updated.

Boom! Boom! Boom! A solar flare triple crown

Three X-class flares erupted in sunspot group 2087 over a 24-hour period on June 10-11, 2014. A portion of the coronal mass ejections from the eruptions may brush the Earth in the next few days. Credit: NASA

Move over California Chrome.  After delivering three X-class flares in two days, sunspot group 2087 wins the triple crown for solar eruptions. And the fun’s not over yet.

The large, complex sunspot region 2087, pictured today June 12 at 8:30 a.m CDT, kicked off three powerful X-class flares on June 10 and 11. More flares are expected from the group in the coming days as it turns toward the Earth. Credit: NASA

Between it and two other spotted regions (2080, 2085) there’s a 60% chance for moderate M-class flares and 30% chance for more X-flares through Saturday. Plus, it turns out that part of the blast from 2087′s double-X flare is whooshing its way toward Earth right now.

Look at all the sunspots! Skywatchers with safe solar filters have a bounty of observing opportunities this week. Catch the big groups 2080 and 2085 (far right) before they rotate over to the sun’s other side. Credit: NASA

Most of the solar plasma blasted sideways off the sun after the eruptions but not all. NOAA space weather forecasters now predict a 20-25% chance of minor auroral storming overnight tonight through Saturday. With each day that passes, region 2087 inches closes to the center of the sun, where it will face Earth more directly, improving the outlook for auroras in the wake of new flares.

New sunspot group enters the stage with guns a-blazing

If ever an “X marked the spot”, this ‘x’ is it. It’s the first of a pair of x-ray flares that popped this morning at 6:42 a.m. CDT in sunspot region 2087. Photo taken in extreme ultraviolet light by NASA’s Solar Dynamics Observatory. Credit: NASA

Sunspot region 2087 announced its arrival on the sun’s southeastern limb today with a real show of firepower. Like a double-barreled shotgun, the group blasted off an X2.2 flare at 6:42 a.m. CDT followed 70 minutes later by an X1.5 at 7:52.

The second flare, an X1.5, peaked around 7:57 a.m. CDT today June 10. Credit: NASA

Although neither was directly in line with Earth, ultraviolet light from the explosions caused a wave of ionization in our planet’s upper atmosphere that affected radio propagation over Europe. Images from NASA’s STEREO solar spacecraft show a coronal mass ejection moving off to one side of the side. It’s not expected to affect the Earth.

The lively sunspot group 2087 has just rotated around the southeastern limb of the sun. 2080 and 2085 are both magnetically complex groups that could spawn M-class flares of their own. Photo taken this afternoon at 1:15 p.m. CDT. Credit: NASA / SDO

Interestingly, the ACE spacecraft, which measures changes in the direction of the magnetic field bundled with the solar wind, dipped south right around the time of the flares. While the two events may be unrelated, anytime the field tilts south, conditions are opportune for the sun’s particle wind to hook into Earth’s magnetic field and possibly fire up auroras.

A large coronal mass ejection, sparked by the double-flare photographed at 9:39 a.m. today by NASA’s STEREO-B spacecraft, expands away from the sun. Credit: NASA

Though it may not be related, the magnetic direction of the wind has been rapidly shifting from north and south all morning and afternoon. Solar astronomers had expected to see flares from sunspot regions 2080 and 2085. Both have complicated delta class magnetic fields ripe with the potential for sparking solar storms. Both also squarely face the Earth. Should an X-class flare erupt in either, the material ejected could wind up producing a geomagnetic storm and accompanying northern lights later this week. So far, they’ve been ‘quiet’ today.

There’s also a chance the plasma cloud released by the X-flare blasts could strike a glancing blow to Earth’s magnetic field; the new group may also continue to produce flares as it rotates into a favorable, Earth-facing position on the sun’s disk.

March monster flare gives NASA an eyeful

A up-close view of the March 29 X-1 flare taken by NASA’s IRIS spacecraft. Flares are colossal explosions that occur when strong magnetic fields – often over complex sunspot groups –  get twisted and then reconnect, releasing vast amounts of stored energy. Credit: NASA

On March 29 this year, sunspot group 2017 unleashed a powerful X1-class flare seen by more telescopes on Earth and in space than any other flare in history.

Four different NASA spacecraft and one ground-based observatory captured photos and data of the solar storm in multiple wavelengths of light. Fortuitously, three of them had been aimed on the group a day in advance in anticipation of a possible eruption.

Views of the flare in three different wavelengths of ultraviolet light made by NASA’s Solar Dynamics Observatory (SDO). The big spikes at left show that the flare was so intense it saturated the instrument’s detector. Credit: NASA

“This is the most comprehensive data set ever collected by NASA’s Heliophysics Systems Observatory,” said Jonathan Cirtain, project scientist for Hinode at NASA’s Marshall Space Flight Center.

Different telescopes shoot at different resolutions. SDO is optimized for taking full-disk photos of the sun. Enlarging the spot group where the flare occurred results in a blurry image (left). At right, the Dunn Solar Telescope provides a much more detailed view. The white patch is the flare in near-visible light. Credit: NASA (left) and NSO

“Some of the spacecraft observe the whole sun all the time,” added Cirtain, “but three of the observatories had coordinated in advance to focus on a specific active region of the sun. We need at least a day to program in observation time and the target – so it was extremely fortunate that we caught this X-class flare.”

In NASA’s RHESSI space telescope, which records extreme temperatures on the sun, the flare appears as a series of three hot spots (purple) superimposed on the IRIS image. The two at left are near the surface; the other high above. Credit: NASA

The battery of instruments involved included three NASA orbiting telescopes – the Interface Region Imaging Spectrograph (IRIS); Solar Dynamics Observatory (SDO); Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI); the Japanese Aerospace Exploration Agency’s Hinode; and the National Solar Observatory’s Dunn Solar Telescope located at Sacramento Peak in New Mexico.


A nice summary of observations made by all the telescopes of the March 29 flare

Instruments on the observatories are planned so that each shows a different aspect of the flare at a different heights above the sun’s surface and at different temperatures. Together they can provided a comprehensive 3D view of one of nature’s most powerful blasts.

The images and video record flare material extending from the solar surface called the photosphere (literally ‘sphere of light’) to more than 3,000 miles high (4,800 km) – well beyond the top of the chromosphere, the lowest level of the sun’s atmosphere.

Cutaway showing the different layers of the sun’s atmosphere. Credit: NASA

Chromosphere means ‘sphere of color’ and comprises the realm of the beautiful flaming red prominences see during total solar eclipses. Temperatures there are hotter than the sun’s 10,000-degree F surface, rising from 11,000 degrees to about 36,000 degrees. Hydrogen gas, what the sun’s mostly made of, glows a deep red at these toasty temps.

Once you reach about 1,250 miles (2,000 km) the chromosphere transitions to the much more extensive solar corona. It’s here that the solar wind originates, that stream of subatomic particles – electrons and protons – blown into space at many miles a second. The violence of solar flares can also blast material out of the corona as a coronal mass ejection.

Flares affect all layers of the sun’s atmosphere. With awesome amounts of data in hand from the March 29 solar storm, scientists are now hard at work teasing out a more detailed picture of how a flare gets started and where it goes from there.

 

Wow, that’s a lot of sunspots! Aurora in the forecast April 19-20

A very busy sun photographed early this morning with NASA’s Solar Dynamics Observatory. Sunspot region 2035 shot off a moderately strong M-class flare on April 16. NOAA forecasters predict a 60% chance for more flares today from one or more of the sunspot groups. Credit: NASA

I can’t recall seeing the sun this peppered with sunspots in a long time. Through the scope this morning I counted nine separate groups. No single spot or group stood out as unusually large, but the combined effect of seeing so many blemishes in one glance made an impression. I encourage you to point your telescope – suitably equipped with a safe solar filter of course – at the sun today to appreciate how fraught with magnetic activity our sun has become.

Each group marks a region on the sun’s shiny outer skin called the photosphere where magnetic energy is concentrated. Strong magnetic fields within a sunspot group quell the turbulent churning of the photosphere, chilling the region by several thousand degrees. Sunspots appear dark against the sun’s blazing disk because they’re cooler.

A powerful solar flare in sunspot region 2036 captured this morning around 8:30 a.m. CDT April 14 in extreme ultraviolet light by the Solar Dynamics Observatory. Credit: NASA

Energy stored in sunspots’ twisted magnetic fields can suddenly be released in violent, explosions called solar flares. Billions of tons of solar plasma – the sizzling mix of protons and electrons that composes the sun – are heated to millions of degrees during the explosion and rapidly accelerated into space. Radiation from radio waves to X-rays and gamma rays fan out at the speed of light. Fortunate for us, our atmosphere and planetary magnetic field protect us from most of what flares can dish out.

The powerful X4.9 solar flare of Feb. 25, 2014 recorded in six different wavelengths of ultraviolet light. Credit: NASA/SDO

Not everything though. Strong X-class flares can cause radio blackouts, damage satellite electronics and disrupt poorly protected power grids. They also can spark displays of northern lights. An M-class flare from sunspot region 2035 on April 16 may kick off auroras overnight Saturday April 19-20. NOAA forecasters predict a 25% chance of a minor auroral storm.


Video of February’s X4.9 flare shown in multiple wavelengths of light

Conditions are ideal if it comes to pass. Moonlight won’t be a problem and night temperatures are decidedly more pleasant than in February.

Aurora alert for northern U.S. tonight Feb. 27-28

Click image to watch video of the X4.9 flare on Feb. 25 in multiple wavelengths of light / Solar Dynamics Observatory

Lots of movement in the northern lights over Hamburg, Germany this evening Feb. 27-28, 2014. Submitted by Daniel Fischer

A spectacular solar X4.9 solar flare from returning sunspot group AR 1967 on Feb. 25 wasn’t supposed to have much affect on Earth. Surprise! Even though the plasma blast shot off to one side of the sun’s disk, our planet’s magnetic bubble received a glancing blow from the explosion this afternoon. Talk about explosion – swarms of electrons and protons left the sun at an estimated 4.4 million mph!

Still image of the X4.9 flare on Feb. 25. Notice that it’s aimed well off to the left. If it had occurred near the center of the disk, its effects on Earth would be more severe. This flare is the strongest yet this year and one of the strongest in the current sunspot cycle. Credit: NASA

As of 5 p.m. CST, a moderate G2 geomagnetic storm is in progress with strong auroras flaring up over across Europe as far south as southern Germany. Should the activity continue, skywatchers in the northern U.S. and possibly farther south will have a good chance at seeing the northern lights tonight. With no moon present, conditions will be ideal for aurora watching. Start looking as soon as possible after twilight ends this evening.

Click HERE to see the extent of the auroral oval, which will help you determine if northern lights might be visible from your location. I’ll update as needed. Good luck!

A quiet affair. The aurora from north of Duluth, Minn. U.S. Thursday night Feb. 27, 2014. Temperature -30 F. Credit: Bob King

UPDATE 9 p.m. CST: Aurora out here in Duluth as a so-far quiet bright arc low in the northern sky.

Big sunspot convulses but all quiet on the aurora front … for now

Sunspot region 1967 is so big it easily popped into view through a “cloud filter” Sunday afternoon Feb. 2. The group is visible with the naked eye properly shielded by a safe solar filter. Details: 350mm lens at f/11, ISO 200 and 1/2000″. Credit: Bob King

What a crazy sunspot cycle. Weeks go by with only a few tiny spots freckling the sun, then all at once a monster group big enough to swallow 10 Earths rounds the eastern limb and we’re back in business. I’m happy to report we’ve got another behemoth snapping and crackling with M-class (moderately strong) flares. That would be Active Region 1967, the hunk a hunk of burnin’ sun we checked out a few days ago.

NOAA weather forecasters predict an 80% chance of continued M-flares and a 50% chance over the next 3 days for considerably more powerful X-class flares. This sunspot group has a delta classification magnetic field, the Facebook equivalent of “it’s complicated”.

Sunspots are made of a dark umbra and lighter penumbra. Very tiny spots with no penumbrae are called pores. A close up of the sun’s photosphere shows a finely granulated texture. Granules are cells of hot gas about the size of Texas that rise from below, cool and sink. Each lasts from 8 to 20 minutes. Credit: NASA

Sunspots have two parts: a dark core (or cores) called an umbra surrounded by a paler skirt of magnetic energy, the penumbra. They can look impressive like this one, but it’s hard to call a sunspot a “thing”. It’s really more of a location on the sun’s bright white photosphere where bundles of powerful magnetic energy bob up from below the surface and insulate a region of the sun’s fiery hydrogen gas from the rest of the flaming globe.

We’re talking insulate as in staying cool. While the photosphere cooks at around 11,000 degrees Fahrenheit, sunspots are some 3,000 degrees cooler. That’s why they appear dark to the eye. If you could rip them away from the sun and see them alone against the sky, they’d be too bright to look at.

Close up of AR 1967 photographed by the Solar Dynamics Observatory at 6:45 p.m. CST Feb. 3, 2014. The group’s shape reminds me of the Big Dipper. Credit: NASA

A delta-class spot group has umbrae of both polarities, north and south, corralled within the penumbra. Like bringing opposite poles of a two magnets so close they snap together, something similar happens inside delta-class groups. Only instead of a snap, a titanic thermonuclear explosion called a flare goes kaboom.The biggest flares release the equivalent of more than a billion hydrogen bombs.

We thank our lucky stars for the 93 million miles separating sun and Earth. AR 1967 has paraded right in front of our noses as it rotated with the sun. Today it squarely faced the Earth – a good thing when it comes to the particle blasts that fire up the northern lights. Let’s hope it showers us with a magnetic goodness in the coming days. I really miss seeing the aurora. You too?

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.