March opens with auroras popping

Rays reach across the northern sky during last night's display of the northern lights. Credit: Bob King

Rays reach across the northern sky during last night’s display of the northern lights. Pardon the quality – it’s a hand-held exposure wedged against my deck railing. Credit: Bob King

Today begins a brand new month and maybe a break from February’s long cold spell. It might also be the start of a new round of auroral activity. Last night a nice G1 geomagnetic storm brought us active streamers and rays across the northern sky. This despite moonlight and, at least for northern Minnesota, pesky clouds, too.

NOAA space weather forecasters are calling for a second round of G1 or minor auroral storms this evening between about 6 p.m. and midnight (CST). Solar disturbances at Earth are rated on a 1 to 5 scale. G1 events usually bring auroras down to the northern tier of U.S. states from Maine to Washington. Other effects include minor fluctuations in power grids and possible impacts on computer hardware in orbiting satellites.

A good way to keep tabs on whether or not the aurora is out is to check the K or Kp index, a measure of magnetic activity in Earth's high atmosphere. The index is updated every 3 hours. The dotted line is 6 p.m. CST (0 hours UT). A Kp index of 5 often means auroras are out in the northern U.S. Credit: NOAA

A good way to keep tabs on the aurora is to check the K or Kp index, a measure of magnetic activity in Earth’s upper atmosphere. The index is updated every 3 hours. The dotted vertical line marks 6 p.m. CST (0 hours UT). A Kp index of 5 indicates a G1 storm is in progress; Kp=6 equals a moderate storm and Kp=9 an extreme event. Click to see the live index. Credit: NOAA with annotations by the author

With a G5 or extreme storm, even Floridians should expect auroras. Satellite electronics and poorly protected power grids can suffer damage, shortwave radio propagation cuts out and induced electric charges in oil pipelines by rapidly changing electrical currents in Earth’s ionosphere can lead to corrosion.

Let’s hope tonight’s predicted aurora brings a similar parade of active rays in the northern sky. Naturally, the moon will be a problem, but if your sky is otherwise dark, you might see a fair show.

This Sun this morning March 1 photographed in UV light by SDO. Credit: NASA

This Sun this morning March 1 photographed in UV light by SDO. Credit: NASA

Like last night, tonight’s source of auroral inspiration is that large, dark “hole” seen in images taken in ultraviolet light by NASA’s orbiting Solar Dynamics Observatory (SDO). Coronal holes are regions small and large on the Sun, where the solar wind of electrons and protons flows freely away from our star at high speeds. All the fluffy yellow plumage in the photo above are magnetic fields that form a sort of canopy over much of the Sun, constraining the flow of particles into space. Holes are free-for-all zones.

Video showing the Sun rotating with a coronal hole

Last night, the magnetic field embedded within the stream pointed south upon its arrival, canceling Earth’s northward-pointing magnetic field and opening a channel into our protective magnetic domain called the magnetosphere. Once “in the building”, the particles shot down into the upper atmosphere and struck atoms and molecules there to create the aurora we saw.

Forecast for midnight tonight Feb. 28-March 1 showing how the auroral oval has expanded southward across southern Canada and the northern U.S. Credit: NOAA

Forecast from last night Feb. 28-March 1 showing how the auroral oval expanded southward across southern Canada and the northern U.S. Credit: NOAA

Besides the K-index described above, another excellent tool to check on aurora is the Aurora 30-minute forecast site. Here you’ll see a near-live view of the auroral oval, the halo of permanent auroras found centered on Earth’s geomagnetic poles. When a storm ensues, the oval (or ovals – there’s a southern one, too) expands southward from its polar lair into southern Canada and the U.S.

The forecast here is for clear tonight, so I’ll be out watching. Check back for an update then.  Good luck!

Coronal holes spark auroras Sept. 26-27 — more possible next 2 nights

The aurora around 1 a.m. CDT this morning. Curious forms twisted away in the northern sky in the Big Dipper. Details: 20mm lens, f/2.8, ISO 1600, 20-second exposure. Credit: Bob King

I apologize for not sending an alert earlier, but I was away from the computer and out under the sky tonight. Streams of solar wind from openings in the sun’s magnetic canopy called coronal holes kicked up auroras overnight for the northern states and Canada.

At 9:15 p.m. Friday night the aurora laid low in the northern sky. The arc is the curved border of the auroral oval that’s centered on Earth’s geomagnetic pole. Credit: Bob King

The display began and remained a very low arc from end of twilight until around 11 p.m. CDT when it slowly widened and brightened. The Kp index reached “4” at that time, not quite a G1 geomagnetic storm but certainly pushing the threshold. Then at 12:20 the arc became brighter and more distinct and split into an exquisite set of short, parallel rays like keys on a piano. Faint rays reached halfway to the zenith as patches of aurora flashed on and off below.

Nice long rays stretch over the forest near Duluth, Minnesota U.S. early this Saturday morning September 27, 2014. Credit: Bob King

While modest, the display was active with a steady supply of rays and pulsating patches, but it never expanded beyond the northern half of the northern sky. Coronal hole effects will linger the next two nights, so be on alert for auroras to appear again.

Hole-y auroras possible tonight Aug. 30-31 / Jupiter returns

The dark opening at the center of the sun’s disk, seen here in ultraviolet light, is a coronal hole photographed on August 28 by the Solar Dynamics Observatory. Holes are ports through which high speed particles from the sun can pour freely into space unconstrained by solar magnetic fields. Credit: NASA

Sometimes it doesn’t take a big solar storm to incite an aurora. Often enough, a hole will do. Midweek, a blizzard of electrons and protons called a coronal mass ejection arrived in Earth’s vicinity, snuck past our magnetic defenses and painted northern skies for several nights in a row with glowing curtains and rays.

Yesterday night, a coronal hole did the same. Coronal holes are openings in the sun’s otherwise ‘locked down’ magnetic canopy. In the photo above, swirls of magnetism form closed loops over most of the sun’s lower atmosphere, keeping the bubbling sea of solar plasma (charged particles) at bay.

Enhancements in the solar wind either from solar storms (CMEs) and coronal holes send a thin soup of electrons and protons into space. If a batch happens to have a southward-pointing magnetic field, it can open a crack in Earth’s northward-pointing field and stimulate oxgen atoms and nitrogen molecules to glow in the upper atmosphere. The aurora is concentrated in two ovals, one hovering over each magnetic pole. Credit: Todd Salat

The sun’s so hot that it energizes and accelerates bits and pieces of itself – electrons and protons – to speeds high enough to escape its gravitational pull. Astronomers call the gust of departing particles the solar wind. Typical speeds hover around 250 miles per second (400 km/sec), but winds leave coronal holes unchecked and can blast into space at up to 500 miles per second (800 km/sec).

When the tempest arrives at Earth and harbors south-pointing magnetism, it links into Earth’s north-pointing magnetic field, sending electrons and protons at high speed down the planet’s magnetic field lines into the upper atmosphere to spark auroras.

Coronal holes are holes where the sun’s magnetic field where the solar wind can escape at high speed. Credit: NASA

NOAA space weather forecasters expect the effects of coronal holes to continue tonight and linger through Monday. Peak possibility for northern lights tonight happens between 10 p.m. and 1 a.m. CDT. Sometimes a particular hole can persist for several solar rotations causing repeat auroras every 27 days.

Stay tuned to Ovation aurora to see if any auroras are dropping south toward your region tonight.  I’ll be in touch.

Jupiter (top) and Venus in bright twilight on August 27, 2014. Credit: Bob King

The other morning while watching aurora I was happy to see that Jupiter had jumped back into the sky. It cleared the trees during twilight and was followed a half hour later by Venus. Low elevation and wiggly air currents meant I couldn’t magnify it much, but at 64x but north and south equatorial belts were unmistakeable.

I always look forward to that first view of Jupiter after conjunction with the sun. We last saw the planet in June, quite a while back. Jupiter’s weather and cloud patterns constantly change. One never knows what to expect when it’s out of sight for a couple months – sometimes an entire equatorial belt can disappear! I’m hear to report that both are still intact.

Aurora watch for northern U.S. overnight April 29-30

Map compiled with satellite data showing the extent of the auroral oval at midnight (CDT) tonight. Credit: NOAA

A stream of high-speed particles from a coronal hole on the sun is blowing by Earth tonight and causing an uptick in auroral activity across Canada. Some of that appears to be spilling into the northern U.S. at this hour, so keep an eye out for a green glow or low arcs spanning the north if your sky is clear. We’re cloudy here in Duluth, Minn. so no first-hand report.

Just for a taste, here’s a beautiful aurora photographed from Faskrudsfjordur in eastern Iceland on April 19, 2014. Credit and copyright: Jónína Guðrún Óskarsdóttir

Will you see tonight’s silvery sliver of a moon? / Aurora watch Jan. 1-2

An 18-hour-old crescent moon photographed with a 12-inch telescope on April 22, 2012. An even younger moon may be visible tonight in the southwestern sky shortly after sundown. Credit: John Chumack and Maurice Massey

2014 begins with a chance to spy an exceptionally thin crescent moon shortly after sunset and possibly the shimmer of aurora at nightfall.

The thin crescent about 1.5 days before new moon on Jan. 21, 2012. Credit: Bob King

The moon’s age is determined by how many hours or days have passed since new moon phase. New moon occurs once a month when the moon lies in nearly the same direction as the sun in the sky. No one can see a new moon because it stays very close to the sun and hides in the glare of daylight.

Under favorable circumstances it’s not too difficult to spot a 1-day-old moon, referred to as a young moon because it’s the first or youngest bit of moon we see after new moon. Young moons are delicate, faint and tucked far down in the twilight glow shortly after sunset.

Spotting a moon fewer than 24 hours old requires planning. You need a flat horizon, haze-free skies and a pair of binoculars. Being on time’s important, too. Be sure to arrive at your observing spot shortly before sundown. Knowing the point on the horizon where the sun sets will guide you to the crescent’s location.

Venus – still visible low in the southwestern sky at dusk – will also be a big help tonight. It’s perfect for getting a sharp focus with your binoculars, essential for seeing the faint lunar crescent clearly. The planet hovers some 7-8 degrees to the moon’s upper left. When you focus on it, you’ll be in for a surprise. I wish I could tell you, but that would spoil the fun.

Diagram showing the sky facing southwest from the Minneapolis area 20 minutes after sunset or at 5:02 p.m. today. The moon will be about 3.5 degrees high at the time. The view will be similar across the Midwest. Further west, the moon will be somewhat higher and closer to Venus. Stellarium

New moon occurred at 5:14 a.m. (CST) today, making tonight’s crescent approximately 12 hours old for skywatchers in the Midwest. Since the moon’s orbit carries it moves east of the sun its own diameter every hour, skywatchers in the western U.S. will have a somewhat easier time of seeing it. From Denver, the moon will be 13 hours old, San Francisco 14 hours and Hawaii 16 hours.

Given that the record for the earliest naked eye sighting of the moon after (or before) new phase is 15 hours 32 minutes and the earliest binocular/telescope observation is 11 hours 40 minutes, most of us will need some kind of optical aid to spy tonight’s silvery sliver.

I recommend a pair of binoculars in the 35mm-50mm range with a generous field of view. Oh, and don’t forget your heavy coat and boots for warmth. Locales with open horizons are generally the windiest places in the world.

Now here’s a lovely view. The waning crescent moon rises above Earth’s atmosphere as seen from the International Space Station. Credit: NASA

Here’s a checklist of what you’ll need:

* Figure out your sunset and moonset times HERE. That way you’ll know exactly when and for how long to watch.

* Thank your lucky stars if the sky is extremely clear and without haze or clouds in the southwest direction.

* Arrive no later than sunset, face toward the direction of sunset and focus your binoculars or telescope on Venus, that brilliant “star” you’ll see about 1 to 2 fists high in the southwestern sky.

* Start looking for the moon 10 minutes after sunset by slowly sweeping the sky just a few degrees above the sunset point. Continue to look for the next 25 minutes giving your eyes an occasional rest and checking focus. You’ll be looking for the thinnest of the thin, no more than a partial arc scratched across the deepening blue.

* If you spy the moon in binoculars, carefully lower them and try to find the moon with your naked eye.

Whether you have success of not, I welcome anyone who attempts this observing challenge to share your observation in our comments section. Good luck to you!

The coronal hole – photographed on Dec. 30 in far ultraviolet light – that might could lead to a chance at seeing the northern lights tonight and tomorrow nights. Credit: NASA

Later this evening and tomorrow as well, there’s a chance that a high-speed stream of particles cut loose from a coronal hole – a open magnetic portal in the sun’s corona that allows electrons and protons to flow freely into space – could kick-start minor auroras at high latitudes. Sometimes that means folks living in southern Canada and along the U.S. northern border can see them too.

You’ll find no lack of sunspot groups on the sun today. This photo was taken by NASA’s Solar Dynamics Observatory this afternoon at 12:15 p.m. CST. Moderate solar flares are possible from Region 1944 (just entering the disk) and departing 1936. Credit: NASA

The sun has recently been more active with an M-class flare yesterday from the 1936 group and the potential for more. Be on the lookout this evening and next for a small display. With little to no moon in the sky, these are good times to look for auroras.

Chance for auroras across northern U.S. tonight Oct. 14-15

Coronal hole aimed at Earth photographed by NASA’s Solar Dynamics Observatory in far ultraviolet light on Oct. 11. Credit: NASA

My meters, graphs and gauges indicate a chance for northern lights overnight for the northern U.S. and southern Canada. Although the official forecast doesn’t sound promising, the Kp index, an indicator of magnetic activity overhead, is in the yellow zone (Kp=4) and satellite plots of the auroral oval show it spreading across Canada and pushing southward toward the U.S. border. This as of 10:30 p.m. CDT.

Either a coronal mass ejection – an outburst of high speed subatomic particles from the sun – or a stronger than usual gust of solar wind from a coronal hole is behind the enhanced activity. Coronal holes are open regions in the sun’s atmosphere not buckled down by solar magnetism. Strong winds of electrons and protons can flow from the holes and spark auroras on Earth.

Unfortunately I can’t do a sky check here in Duluth because the only thing pouring from my sky tonight is rain. Chances for more auroras continue through tomorrow evening Oct. 15-16. As always, keep an eye.

Aurora alert tonight Aug. 27-28

A large coronal hole (dark patch above center) stands out in this photo made in far ultraviolet light this afternoon by NASA’s Solay Dynamics Observer.  Solar wind streams from it may spark minor auroras across the northern U.S. tonight. Credit:NASA/ SDO

Keep watch on the sky tonight if you live in the northern U.S. and southern Canada. The aurora may make an appearance thanks to a brush with gusty solar winds blowing from a coronal hole, an opening in the sun’s magnetic canopy.

Low green arc in the north that reached to about 10 degrees hight (one fist at arm’s length) Tuesday night before moonrise. Credit: Bob King

Activity kicked up to minor storm level (Kp=5) this afternoon spreading auroras across the northern parts of Scandinavia. After a slight dip in the action early this evening, activity may pick up again tonight. Or not. Take a look and let us know if anything shows.

* Update 12:30 a.m. — An auroral arc hung around all evening low in the northern sky seen from Duluth, Minn. US. I never saw any rays, but the camera revealed subtle parallel rays in the arc.

Aurora surprise follows the Perseid shower

The aurora kicked in around midnight with a pretty show of rays and bright green arc in the northern sky this morning. A meteor (top middle) even flashed by during the exposure. Credit: Bob King

With only a slight chance for auroras overnight Aug. 13-14 I was surprised to catch a decent little show starting around 11:30 p.m.  The display peaked about midnight-12:30 a.m. this morning August 14 and then settled back to a quiet arc. That’s where it stands now at 2 a.m. CDT, If your skies are clear it would be worth a look in case activity picks up.

A quiet, low auroral arc in the north around 11:30 p.m. Credit: Bob King

I almost posted an alert before leaving for the countryside to view Neptune and a new comet but all looked quiet at the time. When I arrived, a pale whitish arc hung low in the north. Not 10 minutes later the arc burst into rays that reached 20-30 degrees high. Some were very bright, other like faint fingers.

Ten minutes after the previous photo, the arc sprouted a series of parallel rays. Credit: Bob King

My eyes saw pale green and maybe hints of red, but time exposures with the camera recorded spectacular colors. The likely cause for this show of northern lights is the early arrival of streams of faster-moving solar particles flowing from a large coronal hole in the sun’s northern hemisphere.

Beautiful rays highlight this photo that includes the Big Dipper at left and center. Credit: Bob King

Since so many of you have been out watching the Perseid meteor shower, I’m hoping you caught this surprise gig. Speaking of which, I saw a half dozen shower members this morning and was hardly even trying. The space weather forecast calls for “active” conditions the next couple nights, one level below “minor storm”. I’ll keep you posted.

Chance for auroras in northern U.S. tonight July 25-26

Map showing the extent of the auroral oval just after 11 o’clock Central time this evening based on data from the POES satellite. Credit: NOAA

A strong wind of particles flowing from a solar coronal hole has upped the chances for northern lights at higher latitudes tonight. It may even spread as far south as the northern U.S. As of 11:30 p.m. CDT there was no storm, but activity is up. Keep an eye out just in case.

Tips to help you predict YOUR chances of seeing the next aurora

The sun this morning sports a coronal hole directly facing Earth. Material streams freely from the hole but is bound up in loops of magnetism in other parts of the sun. Credit: NASA

Skywatchers in the northern U.S., Canada and across the Scandinavian countries may have a shot at seeing a modest display of northern lights tonight through tomorrow night. Streams of high-speed solar material flowing from a hole in the sun’s magnetic canopy are expected to arrive later tonight prompting the Space Weather Prediction Center to forecast a G1 geomagnetic storm or in plain English, minor auroras at higher latitudes.

Coronal holes are a regular feature of the sun’s fiery hot atmosphere. Normally, magnetic fields are closed loops that lock down the sun’s gases; holes are regions where the fields open directly into space. Released from their magnetic shackles, electrons and protons in the sun’s atmosphere stream freely into space.

A colorful display of northern lights from the fall of 2004. Credit: Bob King

The solar wind, a dilute soup of electrons and protons, normally blows by the planet at 250 miles per second (400 km/s) but coronal holes send tempests with speeds up to 500 miles per second (800 km/s). When a good-sized hole develops and the sun’s rotation brings it into line with Earth, our protective magnetosphere can gets a pounding.

Speedy particles can squeeze or directly enter the magnetosphere and spark auroras.

I’m often asked where’s the best place to see the aurora. The simple answer is to go north.  The further poleward you live, the better your chances of seeing northern lights. In the northern border states auroras occur with regularity around the time of solar maximum, when the sun peaks in storm activity. The current solar max – the least stormy since 1906 –  happens this summer.

The magnetic north pole, which wanders around due to motions in the Earth’s fluid outer core, is located in northern Canada. Credit: Wikipedia

There’s another consideration. Since the aurora forms a ring centered on the geomagnetic poles rather than on the geographical north and south poles, your chances for spotting it improve if you’re closer to the geomagnetic pole.

For instance, both Denver, Colo. and Madrid, Spain have nearly the same 40 degrees north latitude, but Denver’s in a much better location for an occasional auroral visit because the magnetic pole resides on the “North American side” of the globe.

You can predict the likelihood of northern lights for your location by finding your magnetic latitude. This is much like your regular latitude but as it relates to the magnetic pole instead of the geographic pole. Returning to our example, the magnetic latitude of Madrid is 33 degrees while that of Denver is 48. As far as the aurora is concerned, Denver’s much farther north and in a better position to see a display.

Kp index graph during a bright aurora that lit up mid-latitude skies earlier this month. When the index is yellow, the northern U.S. may see minor auroras. When it’s in the red zone, the aurora is visible further south. Credit: NOAA

I’m always chattering on here about the Kp index, an indicator of geomagnetic or potential auroral activity. It’s rated on a scale of 0 to 9 and updated every 3 hours. The typical threshold for seeing the aurora from Duluth, Minn. (magnetic latitude 56 degrees) is a “4”. If you live in central Canada or northern Norway it can be as low as “3” or “2”.

Another activity level indicator is the POES satellite auroral index rated from 1 to 10+. Here in Duluth, when the level reaches “8” chances are good we’ll see at least a little green haze off to the north. For Denver it has to climb to “10+”.

North American map relating visibility of the aurora to the Kp index. Credit: NOAA

The space weather people have put together a very useful Aurora Tips page you can use to find your own magnetic latitude. A table and drop-down menu list a number of cities, but if you can’t find yours, click on one of the four Kp maps below and then click on your location to get your number. All the maps are also available on the Tips page:

* North America
* Eurasia
* South America and Eastern Pacific
* Africa-Indian Ocean-Australasia

With magnetic latitude in hand, you can now use the tables on the site to know at what level the POES and Kp indices need to reach for you to justify losing sleep for the northern lights. Bear in mind that all these methods are indicators only and don’t absolutely guarantee you will or won’t see northern lights. Other factors like moonlight, weather nature’s unpredictability are always at play.

With the moon now past full and rising late, let’s cross our fingers the aurora will pay a visit soon.