Tag Archives: sun

A 3rd X-class flare rocks the sun

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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.

Sun cuts loose with the biggest flares of 2013

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Various spacecraft views of the flare eruption late Sunday evening

Late on Mother’s Day starting at 9:17 p.m. Central time, the sun unleashed an X1.7 class flare from its backside creating a spectacular display of hot gases. This was followed by an even more powerful X2.8 flare at 11:09 a.m. today. Both rate as the strongest solar blasts of 2013. Particles from the flare left the sun at 1,200 miles per second. Had they been directed toward Earth, power grids as well as satellites could have been affected; we’d also likely have all-night displays of northern lights.

High-speed electrons and protons propelled outward by the X1.7 solar flare expand into space behind the sun over an hour’s time. The particles were moving about 1,200 miles per second. Mercury is the bright object to the left – although it appears to be in the line of fire, it’s not. Credit: NASA/ ESA

This time around the energy and high-speed particles emitted in the flares “went the other way” as far as our planet is concerned. Not so two orbiting observatories. NASA says radiation from the latest flare may stream toward STEREO-B, a sun-watching probe, the Mercury MESSENGER spacecraft and Spitzer Space Telescope, which astronomers use to study the universe in infrared light. Engineers may decide at some point to put them all in safe mode to avoid damage to their sensitive electronics.

In a few days the sunspot region responsible for the flare will rotate onto the sun’s front side. Many are eager for a closeup look at this new bit of activity.

See today’s ring-of-fire eclipse on the Web

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During an annular eclipse like the one that happen later today, a ring of fire encircles the moon (seen in silhouette). Credit: Wikipedia

The New Moon will pass squarely in front of the sun later today treating anyone living along its shadow path to an annular eclipse. That path cuts across Australia, eastern Papua New Guinea, the Solomon Islands, and the Gilbert Islands. Sky watchers across a much broader region of the Pacific including Australia and Indonesia will witness a partial solar eclipse. The rest of us can happily watch it on the Web.

Diagram showing how the sun, moon and Earth are aligned during a total solar eclipse.The moon’s shadow, called the umbra, traces out a narrow path across the Earth’s surface as the moon covers up the sun. An annular eclipse is similar except the umbral shadow doesn’t quite reach Earth, leaving a ring of sunlight exposed.

An annular eclipse happens when the moon is at apogee, its most distant point from Earth in its monthly orbit. Being farther away, it’s too small to completely cover the sun during totality, leaving a narrow ring or annulus of sunlight hanging in the sky like a fiery wedding band.

Earth globe showing the path of today’s annual eclipse (in red). The blue lines show where a partial solar eclipse will be seen. Click image for more details. Credit: Fred Espenak

Unlike a total solar eclipse, where the moon completely blocks the sun and makes its safe to look at, solar filters are required during all phases of an annular eclipse.

That’ll all be taken care of when you head to the Web later today to see the wonder for yourself. The eclipse starts around 5:30 p.m. Central time over Australia. Here are a couple places to check out:

* SLOOH Space Camera. Webcast begins at 4:30 p.m. Central Daylight Time (2:30 p.m Pacific)

* Coca-Cola Space Center. Webcast starts at 4 p.m. Central (2 p.m. Pacific)

* Solar Eclipse Australia.  Start checking around 4:30 p.m. Central time

Click to watch video to help you visualize how the eclipse will play out.

A sunny slant of view on Earth Day

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A halo and circumscribed halo (upper bright saggy arc) around the sun this morning. Both are formed when light is bent or refracted through pencil-shaped hexagonal ice crystals. Photo: Bob King

Happy Earth Day! What a great planet to call home. Situated in our sun’s habitable zone and endowed with life and sweet pleasures, we know of no where else like it. I wouldn’t trade this blue gem for all the planets of Star Trek.

The sun photographed by NASA’s Solar Dynamics Observatory earlier this morning April 22. The large sunspot group at upper right can be glimpsed with the naked eye only through a safe solar filter. Click to enlarge. Credit: NASA

The sun broke through morning clouds today with two pleasant surprises – a colorful circumscribed halo caused by light refracted through billions of microscopic ice crystals in high cirrostratus clouds, and a pair of naked eye sunspots.

Through a safe solar filter, I spied two side-by-side black dots in the upper right (northwest) quarter of the sun.

High-resolution closeup of sunspot group 1726. Sunspots are cooler regions of concentrated magnetic energy on the sun’s surface. They usually have two parts – a dark, inner umbra enclosed by a lighter penumbra. Credit: NASA

They’re part of the large sunspot group 1726 that today spans more than a dozen Earth diameters (approx. 100,000 miles / 160,000 km). The group spawned a few flares, including a moderately strong M-class flare earlier this morning, and holds the potential for more.

Two cool snowpeople catch some April rays last week in Duluth, Minn. Photo: Bob King

In April the sun’s slant in the sky is the same as it is in mid-August, high enough to feel on your cheeks when you walk out the door. It brings welcome relief to some of us still mired in winter with several feet of snow piled up in the yard. The angle of the sun in the sky has much to do with the amount of heat our planet receives and the global climate.

The overhead sun covers a smaller area of ground with the maximum amount of energy (left). At right the sun is shown in winter when its lower angle spreads its light over a larger area with a loss of 100 watts of energy. Result? Colder weather. Credit: Randy Russell / windows2universe.org

If Earth were a gigantic flat disk instead of a sphere and had no atmosphere to filter sunlight, every square meter of ground would receive 1,368 watts of solar energy. Our planet’s spherical shape spreads the sun’s light out over a larger area, diluting the energy received to 342 watts. The atmosphere also filters out a small amount.

A different view of the sun’s angle in winter versus summer and its seasonal energy footprints.  Credit: Nicholas M. Short

When the sun is nearly overhead, as it is during summer, we get the full wattage and really feel the heat just like you would standing next to a 342 watt light bulb. In winter, the sun shines on the planet at a lower angle and its light spreads out broadly across the ground.

Since the amount of energy it’s beaming our way is constant, if it’s spread over a larger area, it becomes less concentrated and weaker. That’s one big reason why winter’s so cold – a lower sun means the intensity (energy) of sunlight is reduced. Without the customary heat to warm air and ground, rain becomes snow and accumulates.

The atmosphere also plays a part. In winter, the low sun shines spends much of the day shining through the lower levels of the atmosphere, where the air is thicker and dustier. Some of that light gets absorbed and some reflected away from Earth, further cooling the season.

Today’s angle suits me just fine. When I walked outside I felt the sun right away and knew it would be good day to celebrate another day of life on the planet. Wishing the same for you.

Concealed planets exposed plus it’s spring break on Mars

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The sun and its pack of planets photographed earlier today by the coronagraph aboard the SOHO observatory. The sun (white circle) is blocked by an opaque disk so astronomers can study the streaky solar atmosphere called the corona. Credit: NASA / ESA

Half the planets have gone into hiding. Mercury is too low in the dawn sky for northern hemisphere skywatchers, and Mars, Venus and Uranus are gathered around the sun concealed by its glare. Only Jupiter and Saturn remain available for our viewing pleasure.

Still, it’s hard to keep planets hidden away when you’ve got the eyes of the Solar Heliospheric Observatory (SOHO) on your side. SOHO orbits around a stable region of space called the L1 Langrangian point where the gravity of Earth balances that of the sun.

SOHO orbits about a million miles ahead of Earth in line with the sun in a small “halo orbit” around the L1 Lagrangian point. From this vantage point it keeps the sun and Earth in view 24/7. Credit: Office of Naval Research

From this prime observing spot, scientists use SOHO’s cameras to study the sun in many wavelengths or colors of light. Special devices called coronagraphs block the overly-bright solar disk with a metal stop to allow viewing of the sun’s outer atmosphere or corona. They also show other objects in the field of view like comets and the current gang of planets – Uranus, Venus and Mars.

Since the planets are very near one another, lots of interesting lineups will happen in the coming days. Venus reaches superior conjunction on March 28 (tomorrow) when it lines up on the opposite side of the sun from Earth. Six hours later it’s only one degree (two full moon diameters) below Uranus. An hour after, Uranus is in conjunction with the sun. Then on April 6-7 Venus and Mars will be in conjunction just half a degree apart. Is this beginning to sound like a barn dance?

One thing to remember about conjunctions – the planets involved are not physically close; they only appear to be because we see them in the same line of sight. If you’d like to watch all these interesting encounters, check out SOHO’s latest coronagraph image.

Approximately every 26 months, Mars passes almost directly behind the sun from Earth’s perspective. During this time, NASA will halt communications with the two rovers. Credit: NASA/JPL-Caltech

For us, Mars’ proximity to the sun is interesting but inconsequential. Not so for the Curiosity mission. On April 17 the planet is in conjunction on the opposite side of the sun from Earth. From our perspective, Mars will appear extremely close to the sun’s brilliant disk. Radiation from solar flares and high-speed subatomic particles in the sun’s corona can disrupt radio transmissions between the two planets during close alignments like this one. To prevent compromised radio commands from reaching either Curiosity or the older Opportunity rover, mission controllers will temporarily suspend transmissions from April 9 to 26.

Wide angle view of Yellowknife Bay taken by one of Curiosity’s hazard avoidance cameras on March 27, 2013. The rover recently resumed science operations after recovery from a computer glitch. Credit: NASA/ JPL

Communications from Mars to Earth will also be reduced. To stay in touch, Curiosity will send daily beeps to Earth. Meanwhile both rovers and orbiting Mars satellites will continue science operations. Data gathered will be stored and then beamed to Earth in early May. The rovers’ spring break will be tame by earthly standards; both will stay put during the interval to prevent any shenanigans.

The bright star Sirius and planet Jupiter perform a balancing act on either side of Orion’s Belt this month and next. This may shows the sky facing southwest around 8:30 p.m. in late March.  Maps created with Stellarium

Did I mention there are still two great planets out at night? Jupiter stands high in the west-southwest at nightfall. It’s the brightest object in that direction. Saturn comes up later around 11 o’clock in the southeast about one extended fist to the lower right of Spica. The full moon will be near Spica tonight and Saturn on Thursday night. Much to see for all!

The full moon will swing by both Spica (tonight) and the planet Saturn tomorrow night. This map shows the sky facing southeast around 11:30 p.m.

Comet PANSTARRS grows fan-tastic tail

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Italian amateur astronomer Lorenzo Comolli captured beautiful symmetric rays called synchronic bands in the dust tail of Comet C/2011 L4 PANSTARRS on March 21, 2013 through his 5.5-inch refracting telescope. Credit: Lorenzo Comolli

I know. You’re probably got PANSTARRS fatigue. Still, I can’t help but direct your eyes once again to yet another wonderful photograph, this one made by Italian amateur astronomer Lorenzo Comolli. Like many of us, he lives in a light polluted area and must escape to find darker skies. For Lorenzo that means a trip to the Alps or Apennines.

Lorenzo with the scope he used to photograph the comet. Credit: Lorenzo Comolli

His spectacular image was made using a 5.5-inch (140mm) wide-field refractor, a sensitive CCD camera and seven images. Each exposure lasted 2 minutes during which time he carefully guided the telescope to follow the comet’s motion across the star field. Lorenzo then stacked all seven images one atop the other in an photo program like Photoshop to create a single, high resolution photo.

Astrophotographers prefer stacking a series of short-exposures instead of making one long exposure because it reduces noise (graininess) and the effects of light pollution. A 14-minute time exposure picks up more unwanted light than a 2-minute one.

Lorenzo added this information to his photo of PANSTARRS. The main tail is composed of very tiny dust particles; the short tail to the left, which tracks along the comet’s orbital path, is formed from the largest, heaviest dust bits. Credit: Lorenzo Comolli

Studying the picture we’re struck by the fan-like spread of multiple plumes of dust released by the comet as the heat of the sun vaporizes dust-laden ices. Cometary dust particles are extremely small, ranging in size from less than a micron (equal to one-thousandth of a millimeter) to 1/100 of a millimeter. For comparison, particles in wood smoke fall in the same range. Sunlight pressure physically pushes these tiny motes back to form the tail.

The real eye-catchers are the synchronic bands. Our best model points to their formation from individual fragments or chunks that break up once they’re released from the comet. As each new fragment crumbles into fine dust, it’s raked into a fresh by sunlight. I think you would agree the end result of such a simple process is breathtaking.

Comolli’s picture also records a dim tail made of sodium atoms, possibly released by collisions between dust grains flying off the comet’s nucleus, and a second dust tail of larger particles trailing behind the comet as it moves along its orbit around the sun. For more of Lorenzo’s images of Comet PANSTARRS, click HERE.

I’ve labeled the different parts of Comet PANSTARRS tail using information from Uwe Pilz on dust particles sizes. Cigarette smoke is 0.01 to 1 micron in size, a level or two smaller what we see for dust in comets. Credit: Lorenzo Comelli

Uwe Pilz of Leipzig, Germany has created a wonderful series of simulations of PANSTARRS’ tail that reveal how dust particles are sorted according to size across the comet’s multiple tails.

I’ve used his information to help you see what’s where in Lorenzo’s photo. Again for reference, a typical bacterium is between 0.2 and 3 microns across (same  as fine comet dust!), a human red blood cell 5 microns and a human hair is about 75 microns but varies by hair type.

While most of us will never see such such riches through our telescopes and binoculars, we can appreciate this hidden side side of PANSTARRS that superb amateur photography can reveal.

St. Pat’s aurora update plus a pleasing lunar lineup tonight

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Green auroral rays topped with pink from earlier this morning near Cloquet, Minn. photographed by Matthew Moses

The sun’s wind of particles has been pounding Earth’s defensive magnetic shield since early this morning. A magnificent display of auroras erupted in response. While hurricane winds can reach over 200 mph, they’re nothing compared to solar wind speeds. Top speed for this storm happened at 5:07 a.m. CDT this morning  when electrons and protons hit the magnetosphere at 477 miles per second (767 km/s) or 1.7 million mph. Of course we’re talking about a very dilute soup of particles compared to the far denser atmosphere, hence the destructive power of a hurricane.

The colorful donut shows the extent of the auroral over at 6:53 p.m. Central time this evening recorded by the POES satellite. Red is a good indicator of strong auroral activity. Let’s hope it’s still there when the U.S. rotates under it later this evening. Credit: NOAA

The storm has continued throughout the day at high levels. Judging by recent satellite plots of the auroral ovals, those vast caps of northern and southern lights centered on Earth’s magnetic poles, residents of the Scandinavia countries, Iceland and Greenland must be experiencing a great light show at the moment.

Auroras look to continue into the evening hours tonight for southern Canada and the northern U.S. once darkness returns. The latest forecast calls for minor storms, but you never know. If it’s clear, walk your dog and keep your eyes to the sky.

Watch the moon slowly slip between Jupiter and Aldebaran tonight. This map shows the sky facing southwest around 10:30 p.m. Central time. Stellarium

Even if auroras fail to materialize, the moon has something fun in store. Tonight it will march  directly between the planet Jupiter and Aldebaran, the brightest star in Taurus the Bull. The three will be closest to a perfect lineup one atop the other around 10:30 p.m. Central time or 8:30 p.m. Pacific. If you look early and then check back a hour or two later, you’ll easily see how quickly the moon moves through the sky as it orbits the Earth.

STEREO beams back stunning new PANSTARRS pics

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STEREO-B photo of Comet PANSTARRS along with planet Earth taken March 13 and processed by Alan Watson. The two vertical white lines are electronic artifacts. Credit: NASA

I thought the first STEREO-B pictures of C/2011 L4 PANSTARRS joined by planet Earth were sweet enough enough. No, no. This one – and the accompanying video – are far nicer. They were made on March 13 when PANSTARRS had more fully entered the telescope’s field of view.

STEREO-A and STEREO-B are twin NASA space probes that study the farside of the sun invisible from Earth stereoscopically. They orbit ahead and behind our planet in its orbit. STEREO-B looks back toward the Earth and comet from its current position in orbit. The diagram show the inner solar system viewed from above Earth’s north pole. Credit: NASA

Relish the many plumes striping the comet’s broad dust tail. Astronomers call them “striae” (STRY-eye or STRY-ee), and they result from the release of massive amounts of dust from vaporizing cometary ices. As they’re blown back by the pressure of sunlight to form the tail, the particles get sorted out into individual plumes according to their varying sizes. Let’s hope that once PANSTARRS gets high enough to see in a darker sky, the beautiful striae will reveal themselves.


STEREO-B video of Comet PANSTARRS and a blast from the sun

The video was compiled using multiple single frames from STEREO-B. The field of view is about 20 degrees (about as wide as the constellation Orion is tall) and the sun is out of the field of field. STEREO-B orbits on the opposite side of the sun from Earth and looks back toward the comet which is fortuitously lined up with the Earth. Amping up the excitement another notch, a coronal mass ejection from the sun appears to be headed for the comet. This is a trick of perspective – the blast missed PANSTARRS by some distance.


Another animation of the comet from March 13 STEREO-B images. Sun is off to the left.

Speaking of distance, you’ll see in the lower left of the orbital diagram that STEREO-B is 1.9 A.U. from Earth. An A.U. or astronomical unit is equal to Earth’s distance from the sun or 93 million miles, so the spacecraft is currently about 177 million miles from our planet. PANSTARRS meanwhile is 1.1 A.U.s from Earth (102 million miles) and very approximately 75 million miles from STEREO-B.

Heads and (many) tails. Comet PANSTARRS on March 15 from Valley Forge National Park, Penn. Credit: John Chumack

I only toss these figures out so you can appreciate the enormity of the comet’s dust tail. The Earth barely registers as more than a blip in the picture. Even accounting for PANSTARRS being some 40% closer to STEREO’s camera than Earth, the tail measures at least a million miles long. Compare that to Earth’s 8,000-mile-diameter and you can begin to appreciate its size.

Comet Hyakutake, which was strode across the spring sky in 1996 had one of the longest tails on record: 354 million miles (570 million km). Credit: NASA

Since comet tails aren’t solid objects, the amount of mass they contain is very small despite appearances. Indeed, they put on a good show!

Comet Hyakutake

STEREO probe snaps portrait of Earth and Comet PANSTARRS

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Comet PANSTARRS joins Mercury and our own planet in this photo taken by STEREO-B on March 10, 2013. Click for large version. Credit: NASA / courtesy Karl Battams

Wow, now isn’t that the coolest! The STEREO-B spacecraft took this photo of Comet C/2011 L4 PANSTARRS and two planets to boot on March 10. NASA’s dual STEREO sun-watching observatories are positioned in Earth’s orbit, one ahead of the planet and one behind. From these two locations they’re able to monitor both the front and backsides of the sun, something otherwise impossible to do from the ground. Their eyes also see background stars down to 13th magnitude, planets and the occasional comet like PANSTARRS.

Animation of photos taken by STEREO-B over an approximately 20 hour period on March 10, 2013. The vertical line below the comet’s head is an artifact. Credit: NASA

Look closely at the comet. Uncompromised by Earth’s atmosphere, we can see four tails.One of the two short spikes is electrified carbon monoxide gas carried away by the solar wind. The other might be made of iron atoms from the iron-sulfur mineral troilite (common in meteorites) blown back by sunlight itself. Two additional tails glow by sunlight reflecting off dust particles released from the comet’s ices as they’re vaporized by the heat of the sun.

Click HERE for maps to help you find Comet PANSTARRS -  from Earth – tonight.

Aurora returns plus a new solar activity forecast

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Rays of pale red and green aurora stripe the northern sky last night March 1, 2013. The tops of the rays reached about two fists high above the horizon. Photo: Bob King

Life can get frantic. That’s why it felt good deep down to watch the slow dance of the northern lights last night. The space weather dudes forecasted a small chance of their appearance, and indicators like the Kp index held steady at just below minor storm level for much of yesterday.

Patchy aurora in Cepheus and Cassiopeia last night. Pale green was visible with the naked eye, but the dimmer reds didn’t register in color except in the camera. Photo: Bob King

The aurora first appeared as little more than a faint glow near the northern horizon shortly before 10 o’clock. It lolled around pushing up occasional faint rays until moonrise. Unlike some other displays, the leisurely weave of this one slowed down my brain and made for a relaxing view. There’s a 10% chance of more minor auroras for the northern U.S. tonight.

Auroral activity is connected to the sunspot or solar cycle. When the cycle reaches its peak approximately every 11 years, we see gobs of sunspots and solar flares are frequent. Material blasted into space during explosive flares and other solar activity is largely responsible for the “juice” behind the northern lights.

In a recent NASA Science News article, solar physicist Dean Pesnell of the Goddard Space Flight Center explores what’s been happening with Solar Cycle 24, the one currently underway. Sunspot numbers shot up in 2011 and early 2012 and then dropped off later that year through early 2013. Peak cycle is predicted for May this year, so what gives?

All solar maxima aren’t created equal. Some are weak, some more energetic and sometimes we get two peaks instead of one.

The blue curve shows the actual sunspot count; the red is what was predicted. Recent sunspot numbers are falling short of predictions. Credit: Dr. Tony Philips and NOAA/SWPC

“The last two solar maxima, around 1989 and 2001, had not one but two peaks, says Pesnell.  Solar activity went up, dipped, then resumed, performing a mini-cycle that lasted about two years. The same thing could be happening now.

The sun displays only small to medium-sized spot groups (labeled) in this photo taken by the Solar Dynamics Observatory at 10 a.m. CST today. Click to see full disk. Credit: NASA

“I am comfortable in saying that another peak will happen in 2013 and possibly last into 2014,” he predicts. Back in 2006 and 2008 a group of solar physicists including Pesnell gathered to forecast the next sunspot cycle maximum. They picked May 2013. In light of flagging solar activity, that now seems unlikely; the new forecast pushes that back to the fall of this year.

There’s one more wrinkle to this story. Pesnell has found similarities between Solar Cycle 14 in the early 20th century, which also had a double-peak, and the current on. If the Cycle 24 plays out in the same way, we might get a peak later this year and another in 2015.

Like the coyote in so many American Indian tales,  nature has stealthy ways that only the watchful eye can untangle.