Biggest sunspot in 5 years may steal the show during today’s eclipse

Active region 2192 (AR 2192) is about the same size as the planet Jupiter or 87,000 miles end to end. This illustration is based on a photo of the  sunspot group taken October 22. Click for more information and animations. Credit: NASA/SDO/Alex Young

Wow, have you ever? Look at that sunspot group. If it seems bigger than any you’ve ever seen you’re right. At least in the last five years. Active region 2192 is the largest sunspot group recorded so far in Solar Cycle 24 which began in 2009. Solar cycles typically last about 11 years and chart the rise and decline of sunspots, flares and other solar activity.

The giant spot group 2192 faces Earth squarely today and should look spectacular during this afternoon’s partial solar eclipse.  Here we see many cooler, darker umbrae surrounded by the lighter penumbrae. The group has a magnetically complex beta-gamma-delta magnetic field ripe for flaring. Credit: NASA/SDO

Yesterday I grabbed my #14 welder’s glass and couldn’t believe how easy it was to see this behemoth. If you have a filter ready for today’s partial solar eclipse, use it to look at the sun anytime, and you’ll see what I mean.

Rarely do naked eye sunspots look like more than dark dots. Region 2192 stands apart. Look carefully through your filter and you’ll discern that the left side (eastern half) looks darker than the western side. That’s because most of the darker bits, called umbrae, are concentrated there.

The sun this morning Oct. 23 with our featured sunspot group facing toward Earth. Credit: NASA/SDO

Sunspots have two parts – a dark core (or cores) called an umbra surrounded by a pale, skirt-like penumbra. Each spot group marks a region on the sun’s fiery outer skin where magnetic energy is concentrated. The magnetic forces that permeate the Sun are the same as those that flow the magnets on your refrigerator but contain vastly more energy because they cover huge regions of the Sun’s surface or photosphere.

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. If you could rip them away from the Sun and see them alone against the sky, they’d be glaringly bright.

The crazy big sunspot group unleashed an X-class flare around 9 a.m. October 22 seen in these photos taken in two “flavors” or far ultraviolet light by NASA’s Solar Dynamics Observatory. Credit: NASA/SDO

Twisty fields of magnetic energy looping above sunspots can become unstable in the hot, turbulent environment of the Sun’s surface, which bubbles and boils like overcooked oatmeal in a microwave oven, and release their pent-up power in violent explosions called solar flares.

2192 has been no stranger to flares. Harboring a complex beta-gamma-delta magnetic field where the magnetic “north poles” and “south poles” lie side by side, they practically beg to explosively reconnect. Since Monday, the spotted beast has spewed two X-class (most powerful) and 8 M-class (medium strength) flares. So far though, none has been directed toward the Earth.


Watch the big group rotate onto the sun’s face and grow in the 72-hour animation made with NASA’s Solar Dynamics Observatory

That’s likely to change very soon since the group is now squarely facing the planet. Already, NOAA’s space weather forecast calls for a 95% chance for more M-class and 55% chance for X-class flare in the next 24 hours. Space weather is expected to be strong during the same period. That might mean auroras coming around as soon as this evening. I’ll keep you posted.

Not only will the sun be eclipsed this afternoon but the planet Venus shines just 1.1 degrees to its north. Venus is very close to superior conjunction which occurs early Saturday. In the photo, the planet is in the background well behind the Sun. Don’t count on seeing Venus – too much glare! This photo was taken from space by NASA’s Solar and Heliospheric Observatory this afternoon using a coronagraph to block the Sun from view. Credit: NASA/ESA

Good luck with today’s eclipse. If you need more information including viewing times for your city, please see my earlier blog on the topic.

Feel the bliss, don’t miss Thursday’s partial solar eclipse

The solar crescents show how much Sun will be covered at maximum for various locations across the U.S. and Canada during the October 23rd (Thursday) partial solar eclipse. Credit: Jay Anderson

Doing anything Thursday afternoon? Have a few minutes to spareThere’s a partial eclipse of the Sun visible across much of North America and of Mexico you might like to catch. For observers in the U.S. and Canadian West the whole event begins and ends in the afternoon before sunset. Those living east of the Great Plains will see the Sun set while still in eclipse.

During a solar eclipse, the orbiting Moon passes between the Sun and Earth, completely blocking the Sun from view as shown here. In Thursday’s eclipse, the moon will pass a little north of a line connecting the three orbs, leaving a portion of the Sun uncovered. To view a partial solar eclipse, a safe solar filter is necessary. Credit: Wikipedia

Solar eclipses occur when the Moon glides between the Earth and the Sun, temporarily blocking it from view. Total solar eclipses get most of the attention because the Earth- Moon-Sun alignment is perfect. Like a snug lid on a pot, the Moon blanks out the Sun completely to create a dramatic spectacle of a black, fire-rimmed disk set in a plush solar corona.

Partial eclipses happen because the Moon’s orbit is tipped a few degrees to the Sun-Earth line. Most months, it passes north or south of the Sun and misses it completely. But during a partial eclipse, the Moon’s close enough to that line to partially block the Sun from view. Unlike a total eclipse, all phases of a partial eclipse are unsafe to view unless you use a safe solar filter or view it indirectly via projection.

Map showing times and percentage of the Sun covered during Thursday’s partial solar eclipse. Times are Pacific Daylight – add 1 hour for MDT, 2 hours for CDT and 3 hours for EDT. Interpolate between the lines to find your approximate viewing time. The arc marked A shows where the eclipse begins at sunset; B = Maximum eclipse at sunset and C = Eclipse ends at sunset. Credit: NASA, F. Espenak,with additions by Bob King

As you can see from the map, nowhere will this eclipse be total. Maximum coverage will happen in Nunavut Territory in northern Canada where the musk oxen might catch sight of a fat solar crescent 81% covered by the moon at sunset. The farther north you live in the U.S. or Canada, the deeper the eclipse. Northern U.S. states will see around 60% covered compared to 40% in the deep south.

In Duluth, Minn. for example, the eclipse begins at 4:21 p.m., reaches a maximum of about 65% at 5:33 p.m. and continues into sunset at 6:06 p.m. Since the sun will be low in the western sky from many locations, be sure to get a spot with a wide open view in that direction.To find out times and coverage for your city, use these links:

* U.S. Cities
* Cities in Canada and Mexico 

Some of the different kinds of safe solar filters available. They work by reflecting or absorbing most of the light from the Sun, allowing only a fraction through to the eyes. NEVER LOOK DIRECTLY AT THE SUN without one. Click photos for a supplier of eclipse glasses. Credit: Bob King

Solar filters come in a variety of styles from inexpensive eclipse glasses that use an optical polymer to glass welder’s filters to caps you place over the front end of a telescope. It’s important to use the correct kind – don’t stack a bunch of sunglasses and figure “it’ll do” or look through smoked glass. They still allow dangerous UV and infrared light to pass through and will mess up your retinas for life.

Because we’re on the heels of the eclipse, if you don’t already have a pair of eclipse glasses I recommend a #14 welder’s glass. It’s my favorite actually because it’s easy to stuff in a pocket and heavy-duty enough to take a few dings. You can pick one up for a few dollars at a welding supply shop. Only buy a #14 – lower numbers won’t cut it.

A piece of aluminum foil, a pin and a cardboard box are all you need to build a pinhole projector. The tiny hole creates a small image of the eclipsed Sun inside the darkened box which you place over your head. Remember to look at the projection of the sun on the inner wall of the box – not through the pinhole itself.

Projection provides a fine alternative to using a filter. You can mount a pair of binoculars (or small telescope) on a tripod and project the Sun’s image on a sheet of white paper or build your own pinhole projector using the instructions above.

You can mount binoculars on a tripod, cover one lens with a lenscap and project the sun’s image safely onto a sheet of white cardboard. Credit: Bob King

If leaves still cling to your trees this season, the narrow spaces between the leaves act like natural pinholes and will cast multiple images of the eclipsed Sun on the ground below.

You can even place one hand atop the other and let the sun shine through the gaps between your fingers to see the eclipse. Low tech as it gets, but works in a pinch.

Here are some other things to watch for during the eclipse:

* If you live where half or more of the sun will be covered, you may notice a change in the quality of daylight. To my eye, the light becomes “grayer”. What do you see?

* Telescope users will see the mountains and crater rims along the moon’s edge as tiny bumps and projections against the brilliant solar photosphere. You’ll also notice how much blacker moon is compared to sunspots. Guess what? We’ve got a huge sunspot out there right now – Region 2192. Perfect for comparison!

Partially eclipsed sun just before sunset seen from Island Lake north of Duluth in May 2012. Credit: Bob King

*  Those living where parts of the eclipse happen at sunset will get an extra special view of the sun with a big bite out of it right sitting atop the southwestern horizon.

I wish you excellent weather – good luck!

 

Mars orbiter sends close-up photos of Comet Siding Spring

High resolution image pairs made with HiRISE camera on MRO during Comet Siding Spring’s closest approach to Mars on October 19. Shown at top are images of the nucleus region and inner coma. Those at bottom were exposed to show the bigger coma beginning of a tail. Credit: NASA/JPL/Univ. of Arizona

They’ve done it again. NASA engineers and scientists successfully slewed the Mars Reconnaissance Orbiter into position to get pictures of comet C/2013 Siding Spring during its close flyby on October 19. I think all of us were waiting for pictures more like this one which show more than a bit of fuzz. Not to disrespect fuzz. Fuzz or comet dust seeded the early Earth with important organic compounds and still makes for awesome meteor showers right up to the present day.

The top set of photos uses the full dynamic range of the camera to accurately depict brightness and detail in the nuclear region and inner coma. Prior to its arrival near Mars astronomers estimated the diameter of the nucleus or comet’s core at around 0.6 mile or 1 kilometer. But based on these images taken at much closer range, its true size is less than 1/3 mile or 0.5 km across. The bottom photos overexpose the nuclear region but reveal an extended coma and a short tail extending to the right.

The Edgeworth-Kuiper Belt extends outward from the plane of the planets, while the Oort Cloud encompasses the solar system in a spherical shell containing millions of comets. Long-period comets like C/2013 A1 Siding Spring often have diagonal orbits that cut across the plane.
Credit: NAOJ

Comet Siding Spring is a new visitor to the inner solar system, hailing from the distant repository of comets called the Oort Cloud far past Neptune and the icy asteroids that populate the Kuiper Belt.

It slid sunward on its cigar-shaped orbit for millions of years as the planets wheeled around the Sun like balls in a roulette wheel. By pure chance, Mars happened to lie only 87,000 miles from the comet on its journey toward the Sun.

Annotated photo of Comet Siding Spring taken by the Opportunity Rover on October 19 near closest approach. The comet passed comet passed much closer to Mars than any previous known comet flyby of Earth or Mars. Credit: NASA/JPL-Caltech/Cornell Univ./ASU/TAMU

Photographing a fast-moving target from orbit is no easy trick. You have to pan the MRO’s camera at the precise rate needed to shoot a time exposure without blurring the image. Engineers at Lockheed-Martin in Denver did exactly that based on comet position calculations by engineers at the Jet Propulsion Lab. To make sure they knew exactly where the comet was, the team photographed the comet 12 days in advance. To their surprise, the orbital calculations were just a bit off. Using the new positions, MRO succeeded in locking onto the comet during the flyby. Without this earlier check, cameras may have missed seeing Siding Spring altogether!

I’ve also added a new, annotated version of the photo taken by the Opportunity Rover and used in the blog earlier today. From the rover’s point of view, the comet buzzed across the constellation Cetus at the time, while here on Earth we see it in the summertime constellation Ophiuchus.

NASA deserves a pat on the back for their great work in acquiring these images and getting them to us within 24 hours. There will be much more on the observational side (and hopefully more photos!) in the weeks and months to come.

Opportunity Rover takes first pictures of Comet Siding Spring from Mars

Comet Siding Spring photographed October 19, 2014 by the Opportunity Rover. Stars show as point and the streaks are probably cosmic ray hits on the sensor during the exposure. Click for original. Credit: NASA/JPL-Caltech

Darn rover’s been there more than 10 years and still producing firsts. Around 4:13 a.m. local time October 19, not long before the beginning of morning twilight, NASA’s Opportunity Rover pointed its panoramic camera at Comet Siding Spring in the constellation Eridanus and took a historic photograph – the first of a comet seen from the surface of another planet.

Another photo of the comet taken by Opportunity. Click for original. Credit: NASA/JPL-Caltech

Sure, it’s just a fuzzy spot, but like Galileo’s first look at Jupiter through his primitive telescope, remarkable all the same. I found the photos while digging through the raw images posted on the Opportunity website earlier this morning. There were only three of the night sky, one of which clearly showed a fuzzy object. If you look closely, the comet looks elongated. That might be from trailing during the time exposure or could be a hint of its tail.

Time exposure of the night sky taken by NASA’s Curiosity Rover on October 19. You can see real stars if you look closely but most of the specks are noise. No sign of the comet. Credit: NASA/JPL-Caltech

Unfortunately I couldn’t find the comet in the several pictures returned by the Curiosity Rover. Each is heavily speckled with noise but no matter how I tried to tone and stretch the photos, no comet. Maybe NASA has other pictures it will offer after they’re cleaned up.

Map showing the landing sites of rovers and probes successfully landed on Mars. Opportunity is located 1.9 degrees south of the Martian equator in the dark feature called Sinus Meridiani. Credit: NASA

I should emphasize here that we’re still awaiting confirmation from NASA that these pictures really do show the comet, but it appears to be the real thing.

Next to a greatly overexposed Mars, we see Comet Siding Spring continuing on its way today October 20, 2014. Copyright: Rolando Ligustri

Mars probes A-OK after dramatic comet flyby

This artist’s concept shows NASA’s Mars orbiters lining up behind the Red Planet for their “duck and cover” maneuver to shield them from comet dust from the close flyby of comet Siding Spring (C/2013 A1) on Oct. 19, 2014. Credit: NASA

All three U.S. spacecraft orbiting the Red Planet reported back in good health after their close encounter with Comet Siding Spring this afternoon. The Mars Reconnaissance Orbiter, Mars Odyssey and Mars Atmosphere and Volatile Evolution (MAVEN) took shelter behind Mars during the half-hour when the comet’s dust particles posed the greatest hazard for the probes. Each also gathered data on the comet before during and after the approach. Click on the links to check the mission status of each orbiter.

This illustration shows where the comet was in the sky above the rover when it was taking photos earlier this evening. Hopefully, we’ll see them soon. Credit: NASA

So far, so good. Meanwhile, NASA’s Curiosity Rover shot photos of fleeing, dirty ice-ball between 4-6 p.m. Central Daylight Time as skies darkened after sunset in Gale Crater. No pictures have been posted yet, but I’ve been monitoring websites and feeds like a mall security officer.


Come Siding Spring comes out the other side!

As for the comet, it survived its brush too. Photos and videos made during and after the encounter clearly show Siding Spring passing Mars intact. The video was made from still photos shot earlier this evening by Fritz Helmut Hemmerich from 3,900 feet in Tenerife in the Canary Islands.

Set the alarm and boil the tea, it’s time for the Orionid meteor shower

The Orionids peak Tuesday and Wednesday mornings Oct. 21-22 next week when an observer might see 20-25 meteors an hour from a dark sky. They’ll appear to radiate above Betelgeuse in northern Orion. Source: Stellarium

The coming week’s menu features a meteoric tossed salad of Taurid fireballs crossing paths with the annual Orionid meteor shower. While the Taurids are a broad, sparse stream coming in dribs and drabs throughout October and November, the Orionids peak on the mornings of October 21-22. Expect to see 20 meteors an hour emanating from a point of sky above the bright star Betelgeuse in the hunter’s shoulder.

Each streak of light you see signals the incineration of a flake of Halley’s Comet, the parent comet of the Orionids. Every year in late October, Earth cuts across Halley’s orbit and bits of dust shed by the comet from previous passes near the sun burn up as they strike the upper atmosphere at speeds of around 148,000 mph.

Composite of a recent Orionid meteor shower taken with an all-sky camera. Credit: NASA

It’s been a couple years since I’ve seen the shower due to clouds or moonlight, but to the patient observer they’re thrilling to watch. Orionids are extremely fast – most tear across the sky in a second or less. Don’t even bother to alert your observing companions if you see one. It’ll be long gone even as the words leave your mouth, though if you’re lucky, some meteors will leave glowing trails of ionized air or even a curl of cosmic smoke (dust) in their wakes.

“The Orionid meteor shower is not the strongest, but it is one of the most beautiful showers of the year,” says Bill Cooke, head of NASA’s Meteoroid Environment Office.

Composite photo of an Orionid meteor shower taken a few years ago. The constellation Orion is seen at lower right center. Credit: SLOOH

This year’s shower won’t be compromised by moonlight either. It may even be enhanced by it. On Tuesday morning, a fingernail crescent will attempt to steal the show as it rises in the east at the start of morning twilight. Which brings us to the best time to view the Orionids.

I’ve drawn the map above for 2 a.m. local time. That’s when the radiant is high enough in the sky for a good show to begin, but the hours just before dawn are a tad better as the radiant point is higher yet. The ideal time would be from 3-6 a.m. Find a place where light pollution is at a minimum and set up facing south-southeast for the best view. A comfy reclining chair and blanket or sleeping bag will help you stay relaxed and warm. It is almost November after all!

Monster sunspot could stir up auroras

The sun photographed this morning by NASA’s Solar Dynamics Telescope at 11:30 a.m. CDT this morning October 18. Credit: NASA

Not today and not tomorrow, but a monster sunspot group rounding the eastern limb of the sun could spunk up the fall aurora season. Active region 2192 harbors a Jupiter-sized sunspot that’s just now visible with the naked eye using a safe solar mylar filter or #14 welder’s glass. I spotted it very close to the southeastern edge of the sun today. In the coming days, it will rotate into better view, making for an easy catch with the naked eye or small telescope. I can’t emphasize enough the importance of a safe filter. You can purchase one HERE for naked eye viewing or HERE for your telescope.

Coronal mass ejection shot out by flare activity in new sunspot group 2192 on October 14 before it even rounded the sun’s limb. Image from the SOHO coronagraph. Click for video. Credit: NASA/ESA

Even before the behemoth came into view, it spawned a brilliant coronal mass ejection on October 14 and several M-class medium strength flares. If we assume that the giant spot stays potent, the sun will rotate it around to face Earth in about 6 days. Flaring and other activity would then stream in our direction.

It will also spice up the partial solar eclipse next Thursday afternoon. Watch for the black limb of the moon to not only eclipse the sun but this sunspot too!

Update: Sunspot group 2192 unleashed an strong X-1 class flare around midnight Oct. 18-19. Any material it may have launched into space would have missed Earth by a wide margin because of the group’s position near the sun’s edge.

Comet-Mars encounter coming Sunday: See it through Martian eyes

Simulation of how comet C/2013 Siding Spring will appear in Martian skies around midnight October 18-19, 2014 from the Curiosity rover’s location near Mars’ equator. Credit: Solarsystemscope.com

No one knows exactly how Comet Siding Spring will look from the Red Planet when it blows by just 83,263 miles (134,000 km)  from its surface. Certainly a whole lot brighter than we see it from Earth!  The close shave will happen around 1:28 p.m. CDT this Sunday October 19th.

I spotted it last night at about magnitude +11 not far from Mars in a 15-inch (37-cm) telescope from northern Minnesota. The comet was a faint smudge, but then my eyes were 151 million miles from the duo. Distances like can suck the drama right out of a comet. Seen up close from Mars, it would drop the jaws of a entire crew of astronauts.

If Comet Siding Spring were passing by Earth instead of Mars it would be only 1/3 the distance of the moon from Earth. Credit: NASA

When nearest, Siding Spring is expected to shine at magnitude -5 or about twice as bright as Venus. Mind you, that estimate considers the entire comet crunched down into a dot. But for those who remember, Comet Hale-Bopp’s appearance in spring 1997, it shown at zero magnitude, 100 times fainter than Siding Spring, and made for one of the most impressive naked eye sights in years.

More recently, Comet McNaught climaxed at magnitude -5 in the daytime sky near the sun in January 2007. It was plainly visible in binoculars and telescopes in a blue sky if you knew exactly where to look and took care to avoid the sun. Martians will be far luckier as their comet will appear in a dark sky.


Comet C/2013 Siding Spring as it rises and sets over the Curiosity Rover this weekend October 18-19. Click the control to start, to pause and for other options. Credit: Solarsystemscope.com

To help you picture it the folks at Solarsystemscope.com, famed for their simulations of the dearly departed Comet ISON, have created another gem, a look at Comet Siding Spring as it wheels across the robotic gaze of the Curiosity Rover in the next few nights.

Artist view of the comet passing closest to Mars this Sunday. At the time, the Mars orbiters from the U.S., Europe and India will be huddled on the opposite side of the planet to avoid possible impacts from comet dust. Credit: NASA

Seen from Mars, the comet bobs along Eridanus the River southwest of Orion, passing high in the southern sky overnight. What a sight! The comet nucleus is only about 0.4 miles (700 meters) across, but the coma or atmosphere fluffs out to around 12,000 miles (19,300 km). Seen from the ground, Siding Spring would span about 8°of sky or 16 full moons from head to tail. Moving at 1.5° per minute, it will be fast enough to see crawl across the heavens in real time with the naked eye. Ah, if only we could be there.

Rest assured we’ll get the latest images and results from the rovers and orbiting spacecraft posted here asap.

Comet Siding Spring seen from Earth as it crosses the rich star clouds of the constellation Ophiuchus on October 16. Credit: Damian Peach

As usual, several outlets will be featuring live webcasts and special programs Sunday. Here are two:

* SLOOH starting at 1:15 p.m. CDT (6:15 p.m. UT) Sunday Oct. 19
* Gianluca Masi’s Virtual Telescope site starting at 11:45 a.m. CDT (4:45 p.m. UT)

An exciting weekend lies ahead!

Rosetta update Oct. 16 – new selfie, landing site close-up, more great videos

Rosetta’s Philae lander snapped a ‘selfie’ at comet 67P/Churyumov–Gerasimenko from a distance of about 9.9 miles from the surface of the comet. The image was taken on October 7 and captures the side of the Rosetta spacecraft and one of Rosetta’s 46-foot-long (14-m) solar wings, with the comet in the background. Click to enlarge. Copyright: ESA/Rosetta/Philae/CIVA

Scope out these new images from the Rosetta probe now less than a month away from dropping the Philae lander onto Comet 67P C-G’s dusty-icy surface. The first picture was taken by the the landers’ Comet Infrared and Visible Analyzer (CIVA) looking out from Rosetta toward the comet. You might remember Philae’s first selfie back on September 7 taken from 31 miles (50 km) away. This new image brings us to within 9.9 miles (16 km) of the comet’s surface.

The photo’s a composite of two images made with two separate exposures to capture the dark comet and Rosetta insulation (one exposure) and the bright solar array. The image is the last from Philae before the lander separates from Rosetta on November 12 and gently floats down to the comet’s surface.

Not only is the comet larger in the new photo but a very distinct jet of gas of vaporizing ice and dust is visible near the junction of the neck and larger lobe.

A new mosaic image from the Rosetta spacecraft shows Philae’s primary landing site up close. Touchdown is expected at 10 a.m. CST on Nov. 12  Click to enlarge. Credit: ESA/Rosetta/MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA

A new mosaic image from Rosetta spacecraft shows Site J, the primary landing site on Comet 67P/Churyumov-Gerasimenko for the mission’s Philae lander. Rosetta is the first mission to orbit a comet and to attempt a soft landing on one.

The mosaic comprises two images taken by Rosetta’s OSIRIS narrow-angle camera on Sept. 14, 2014, from a distance of about 19 miles (30 kilometers). The image scale is 1.6 feet (0.5 meters) per pixel. The red ellipse is centered on the landing site and is approximately 1,600 feet (500-m) in diameter or a third of a mile. That’s just a walk around the block!


New video from Mattias Malmer titled “Rising over the edge” – A synthetic 3D view of 67P / Churyumov-Gerasimenko October 8

On November 12, the Rosetta spacecraft will release Philae at 3:03 a.m. Central Standard Time (9:03 a.m. Greenwich Time); 7 hours later it will land at Site J at around 10 a.m. CST (4 p.m. Greenwich).


Cheops Ascent by Mattias Malmer

If you like that video, here’s another in 3D (use red-blue anaglyph glasses to see best). Cheops is the name of the boulder in the photo located on the neck of the comet. It’s about 148-feet (48-m) across. The “synthetic” in the video titles refers to Malmer’s method creating them. He takes real images and digitally drapes them on a model of the comet to create a three-dimensional appearance.

Auroras in the north tonight Oct. 14-15

Aurora low in the northern sky around 10:30 p.m. CDT this evening October 14, 2014. Credit: Bob King

Earlier this evening, a glancing blow from a solar blast that left the sun on October 10th jiggled Earth’s magnetic domain to produce a modest display of northern lights. Forecasters originally expected the coronal mass ejection (CME) to miss Earth. My astronomy class and I noticed a low arc in the north as early as 8:30 p.m. A half hour later, the arc broke apart into a beautiful set of evenly-spaced rays across the northern sky.

These slowly faded back to a quiet glow as if the aurora decided to take a nap and then re-brightened about 9:30. Right now at 11 p.m. the display has returned to a quiet arc about 5 degrees above the northern horizon directly below the Big Dipper. Something about it reminds me of a pale green feather boa.

The Kp index, a measure of how magnetically disturbed the upper atmosphere is, hit 5 this afternoon and evening, the mark of a minor geomagnetic storm. Auroras are usually seen across the northern border states when Kp=5. Credit: NOAA

NOAA space weather shows a G1 minor geomagnetic storm underway since the afternoon. Activity may be dropping off now, but it’s hard to say for sure, so keep a lookout for auroras tonight if you live in the northern states and southern Canada. Besides aftereffects of the solar blast, a chance for more auroras will continue the next couple nights due to “solar sector boundary crossings”. These are changes in the direction of the magnetic field within the solar plasma (electron and proton mix) that continually streams from the sun called the solar wind.