Ron Cottrell captured the sunspot in all its swirly magnetic goodness in hydrogen-alpha light on October 19. To appreciate its size, he included the Earth (lower left) for reference. Credit: Ron Cottrell
That’s one big, black blemish on the Sun today! Rarely have we been witness to such an enormous sunspot. Lifting the #14 welder’s glass to my eyes this morning I about jumped back and bumped into the garage.
Properly shielded, it was very easy to see with the naked eye. Unlike some other naked eye sunspots, this one showed structure. The eastern end was darker, the western half grayer and more extended.
Watch the giant spot rotate into view and grow right before your eyes in this 72-hour time-lapse video taken by SOHO’s HMI imager Oct. 18-20, 2014
Through a small telescope, the mix of dark umbras scattered amid weirdly sculpted penumbral “islands” was incredible to see. Photographs like the one above are wonderful documents, but witnessing this beautiful complex magnetic mess with your own eyes is another experience altogether. Region 2192 continues to grow and size and complexity and is now the largest sunspot group of solar cycle 24which began in 2009 – more than five years ago!
Active region 2192 is now the largest sunspot group to appear in over five years. Compare to Jupiter and the Earth. Credit: SDO/HMI/Alex Young
Every sunspot 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. Cooler meaning 8,000 F instead of 11,000 F, so yes, they’re still VERY hot.
Watch as Region 2192 crackles with energy and flares as seen in far ultraviolet light with NASA’s Solar Dynamics Observatory.
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 fans out at the speed of light. Fortunately for us, our atmosphere and planetary magnetic field protect us from most of what flares can fling our way.
NASA’s Solar Dynamics Observatory took this photo of the Sun and Jupiter-sized sunspot region 2192 this morning Oct. 22 at 8:45 a.m. CDT. The view in a small telescope equipped with a safe solar filter is even better! Credit: NASA
But as the Sun rotates this monster into our line of sight, possibilities for Earth-directed flares and coronal mass ejections increase as do geomagnetic storms, the bringer of auroras. Already in the past 48 hours, the spot has dished out seven M-class flares and a powerful X-1 flare even before it has fully come into view. There’s more to come – Region 2192 harbors an unstable beta-gamma-delta magnetic field ripe for additional flaring including more of the X-classvariety.
The Sun on October 21 showing smaller sunspot regions along with our featured group. Credit: Sarah and Simon Fisher
There’s no doubt now that this behemoth will stick around to add a whole new dimension to tomorrow’s partial solar eclipse. I can’t wait to see the Moon’s black curve approach and at least partially occult the group from view. If you’re interested in getting some one-of-a-kind pictures of the scene, please see our own Dave Dickinson’s excellent guide on photographing the partial eclipse.
A sliver of a Moon rises in morning twilight today October 22 just a day away from its appointment with the Sun. Credit: Bob King
While we’re on the Moon, early morning risers had the pleasure of its company just one day before New Moon and solar eclipse. I was out watching the Orionid meteor shower. While not rich like the Perseids or Geminids I managed to catch a few including a few lucky shots with the camera.
An Orionid meteor slashes across the top of the frame directly above the constellation Orion early this morning October 22, 2014. Details: 24mm lens, f/2.8, 30-seconds at ISO 1600. Credit: Bob King
The shower has peaked but will still be active the remainder of the week if you’re inclined to take a look. And I can’t resist. How about one last sweet close-up photo of sunspot group 2192? I have a feeling you won’t mind.
Monster Sunspot AR12192 taken by Karzaman Ahmad on October 21, 2014, from Langkawi Nagtional Observatory, Malaysia. Credit: Karzaman Ahmad and shared at spaceweather.com. Click the image to see additional animations and photos on Alex Young’s site
It’s a-comin’: a “monster” sunspot is steadily rotating around the Sun’s southern hemisphere and will soon be in position to fire flares and CMEs in our direction — and this past weekend master solar photographer Alan Friedman captured it on camera!
The image above was taken in full-spectrum visible light on Sunday, Oct. 19 by Alan from his backyard in Buffalo, New York. Sunspots 2186 (at the top limb), 2187 (upper center), 2193 (the small middle cluster) and the enormous AR2192 are easily visible as dark blotches – “cooler” regions on the Sun’s surface where upwelling magnetic fields interrupt the convective processes that drive the Sun’s energy output.
This particular image was a single frame of video, unlike some of Alan’s other photographs. According to Alan the air turbulence was particularly bad that day, shooting between the clouds, so only this one frame was usable. Click the image for full-scale “wow” factor.
(And if you think AR2192 looks scary in that image, check it out in CaK bands here!)
Scale size of Earth compared to AR2192 on Oct. 20 (NASA/SDO/AIA. Diagram by J. Major.)
According to Spaceweather.com AR2192 has grown considerably over the past few days and has the potential to unleash M- and X-class flares in our direction now that it’s moving into Earth-facing position. It’s currently many times larger than Earth and will likely get even bigger… in fact, during this week’s partial solar eclipse AR2192 should be visible with the naked (but not unprotected!) eye for viewers across much of North America.
The partially eclipsed sun sets over Island Lake north of Duluth, Minn. on May 20, 2012. Credit: Jim Schaff
2014 – a year rich in eclipses. The Moon dutifully slid into Earth’s shadow in April and October gifting us with two total lunars. Now it’s the Sun’s turn. This Thursday October 23 skywatchers across much of the North America and Mexico will witness a partial solar eclipse. From the eastern U.S. the eclipse will reach maximum around the time of sunset, making for dramatic picture-taking opportunities. Further west, the entire eclipse will occur with the sun up in the afternoon sky. Either way, you can’t go wrong.
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 at New Moon when the Moon passes between the Sun and the Earth and blocks the Sun from view. During a total solar eclipse, the Sun, Earth and Moon are exactly aligned and the Moon completely hides the brilliant solar disk. Partial eclipses occur when the Moon passes slight north or south of the line connecting the three bodies, leaving a slice of the Sun uncovered. For that reason, a safe solar filter is required to protect your eyes at all times. We’ll delve into that in a minute, but first let’s look at the particulars of this eclipse.
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
Nowhere will this eclipse be total. At best, polar bears and musk oxen in Canada’s Nunavut Territory near Prince of Wales Island will see 81% of the sun covered at sunset at maximum eclipse. Most of the rest of us will witness about half the Sun covered with the northern U.S. getting around 65% and the southern states closer to 40%. In Minneapolis, Minn. for instance, the eclipse begins at 4:23 p.m. CDT, reaches a maximum of 62% at 5:35 p.m. and continues on till sunset at 6:14 p.m. For times, coverage and other local circumstances for your town, click over to U.S. cities and cities in Canada and Mexico.
Safe solar filters come in several varieties ranging from plastic glasses to a #14 welder’s glass for visual observation and snug-fitting optical filters that fit over the end of a telescope. Credit: Bob King
There are several ways to observe a partial eclipse safely, but they all start with this credo: Never look directly at the Sun. Dangerous ultraviolet and infrared light focused on your retinas will damage your vision for life. Nothing’s worth that risk. Happily, filters and indirect viewing methods are available. Eclipse glasses fitted with mylar or polymer lenses are a great choice. I’ve used them all but my favorite’s still the classic #14 welder’s glass because it slips in the pocket easily and takes a beating. Make sure it’s a #14, not a #13 or lower.
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
Telescopes should be outfitted with an optical mylar or aluminized glass solar filter that fits snugly over the top end of the tube. A welder’s glass gives a green solar image, mylar a blue one and black polymer a pale orange. Filters work by only allowing a fraction of the Sun’s light to reach the eye. At the end of this article I’ve listed several sites that sell a variety of safe solar filters for naked eye and telescopic use.
Easy guide to building a pinhole projector for solar eclipse viewing
Indirect methods for safe viewing include projecting the Sun’s image through a small telescope or pair of binoculars onto a sheet of white paper or cardboard. You can also build a pinhole projector shown in the video above. A box and piece of aluminum foil are all you need.
Tiny gaps along the length of this palm frond created a series of solar crescents during the July 1991 eclipse. Credit: Bob King
If for some reason you aren’t able to get a solar filter, all is not lost. The tiny spaces between leaves on a tree act like pinhole projectors and will cast hundreds of images of the Sun on the ground below during the eclipse. To see the effect even better, bring along a white sheet or blanket and spread it out beneath the tree. You can even cross your hands over one another at a right angle to create a pattern of small “holes” that will reveal the changing shape of the Sun as the eclipse proceeds.
The white crescents show how much of the Sun will be visible from a variety of locations at maximum eclipse. The farther north you go, the deeper the eclipse. Credit: Jay Anderson
Now that you’re rockin’ to go, here are some other cool things to look for during the eclipse:
* Sunspots appear black when viewed through a filtered telescope, but they’re no match for the opaque-black Moon silhouetted against the Sun. Compare their unequal degrees of darkness. With a little luck, the giant sunspot region 2192 will provide a striking contrast with the moon plus add interest to the eclipse. This region only recently rotated onto the Sun’s front side and will be squarely in view on Thursday.
* The moon may look smooth and round to the eye, but its circumference is bumpy with crater rims and mountain peaks. Watch for these tiny teeth to bite into the solar disk as the eclipse progresses.
* From locations where half or more the Sun’s disk is covered, look around to see if you can tell the light has changed. Does it seem somehow “grayer” than normal? Is the blueness of the sky affected?
As I learned from comet discoverer and author David Levy many years ago, every eclipse involves the alignment of four bodies: Sun, Earth, Moon and you. We wish you good weather and a wonderful eclipse, but if clouds show up, you can still watch it via live stream on SLOOH.
UPDATE: Not only will the sun be eclipsed Thursday afternoon but the planet Venus will shine just 1.1 degrees to its north. Venus is just two days from superior conjunction. In the photo, the planet is in the background well behind the Sun. Don’t count on seeing it – too close and too much dangerous glare! This photo was taken from space by NASA’s Solar and Heliospheric Observatory early Thursday Oct. 23 using a coronagraph to shade the Sun. Credit: NASA/ESA
Solar filter suppliers – for a #14 welder’s glass, check your local phone book for a welding supply shop:
* Thousand Oaks Optical — Large variety of solar filters for telescopes and cameras. Sheets of black polymer available if you want to make your own.
* Rainbow Symphony — Eclipse glasses and solar viewers as well as filters for binoculars and telescopes. The basic glasses cost less than a buck apiece, but you’ll need to buy a minimum of 25 pairs.
* Opt Corp — Offers high-quality Baader mylar optical filter material to make your own.
* Orion Telescopes — Glass and mylar filters for telescopes and binoculars.
* Amazon.com – Filters for naked eye use
Comet C/2013 A1 Siding Spring passed between the Small Magellanic Cloud (left) and the rich globular cluster NGC 130 on August 29, 2014. Credit: Rolando Ligustri
We present here a compendium of Universe Today articles on comet Siding Spring. Altogether 18 Universe Today stories and counting have represented our on-going coverage of a once in a lifetime event. The articles beginning in February 2013, just days after its discovery, lead to the comet’s penultimate event – the flyby of Mars, October 19, 2014. While comet Siding Spring will reach perihelion just 6 days later, October 25, 2014, it will hardly have sensed the true power and impact that our Sun can have on a comet.
Siding Spring’s Oort Cloud cousin, Comet ISON in November 2013 encountered the Sun at a mere 1.86 million km. The intensity of the Sun’s glare was 12,600 times greater than what Siding Spring will experience in a few days. Comet ISON did not survive its passage around the Sun but Comet Siding Spring will soon turn back and begin a very long journey to its place of origin, the Oort Cloud far beyond Pluto.
An animation of comet Siding Springs passage through the inner Solar System. The scale size of its place of origin would dwarf the orbits of the Solar System to little more than a small dot. (Illustration Credit: Near-Earth Object (NEO) office, NASA/JPL)
The closest approach for comet Siding Spring with the Sun – perihelion is at a distance of 1.39875 Astronomical Units (1 AU being the distance between the Earth and Sun), still 209 million km (130 million miles). The exact period of the comet is not exactly known but it is measured in millions of years. In my childhood astronomy book, it stated that comet Halley, when it is at its furthest distance from the Sun, is moving no faster than a galloping horse. This has also been all that comet Siding Spring could muster for millions of years – the slightest of movement in the direction of the Sun.
It is only in the last 3 years, out all the millions spent on its journey, that it has felt the heat of the Sun and been in proximity to the planetary bodies of our Solar System. This is story of all long period comets. A video camera on Siding Spring would have recorded the emergence and evolution of one primate out of several, one that left the trees to stand on two legs, whose brain grew in size and complexity and has achieved all the technological wonders (and horrors) we know of today.
Now with its close encounter with Mars, the planet’s gravity will bend the trajectory of the comet and reduce its orbital period to approximately one million years. No one will be waiting up late for its next return to the inner Solar System.
It is also unknown what force in the depths of the Oort cloud nudged the comet into its encounter with Mars and the Sun. Like the millions of other Oort cloud objects, Siding Spring has spent its existence – 4.5 Billion years, in the darkness of deep space, with its parent star, the Sun, nothing more than a point of light, the brightest star in its sky. The gravitational force that nudged it may have been a passing star, another cometary body or possibly a larger trans-Neptunian object the size of Pluto and even as large as Mars or the Earth.
The forces of nature on Earth cause a constant turning over geological features. Our oceans and atmosphere are constantly recycling water and gases. The comets that we receive from the Oort Cloud are objects as old as our Solar System. Yet it is the close encounter with Mars that has raised the specter of an otherwise small ordinary comet. All these comets from deep space are fascinating gems nearly unaltered for 1/3rd of the time span of the known Universe.
An image of a May 9, 2014 coronal mass ejection from the Sun using data from both the Interface Region Imaging Spectrograph (IRIS) spacecraft and the Solar Dynamics Observatory. Credit: NASA, Lockheed Martin Solar & Astrophysics Laboratory
My, the Sun is a violent place. I mean, we knew that already, but there’s even more evidence for that using new data from a brand-new NASA spacecraft. There’s talk now about tornadoes and jets and even “bombs” swirling amid our Sun’s gassy environment.
A huge set of results from NASA’s Interface Region Imaging Spectrograph (IRIS) spacecraft reveals the true nature of a mysterious transition zone between Sun’s surface and the corona, or atmosphere. Besides the pretty fireworks and videos, these phenomena are telling scientists more about how the Sun moves energy from the center to the outskirts. And, it could tell us more about how stars work in general.
The results are published in five papers yesterday (Oct. 15) in Science magazine. Below, a brief glimpse of what each of these papers revealed about our closest star.
Bombs
This is a heck of a lot of energy packed in here. Raging at temperatures of 200,000 degrees Fahrenheit (111,093 degrees Celsius) are heat “pockets” — also called “bombs” because they release energy quickly. They were found lower in the atmosphere than expected. The paper is here (led by Hardi Peter of the Max Planck Institute for Solar System Research in Gottingen, Germany.)
Tornadoes
It’s a twist! You can see some structures in the chromosphere, just above the Sun’s surface, showing gas spinning like a tornado. They spin around as fast as 12 miles (19 kilometers) a second, which is considered slow-moving on the Sun. The paper is here (led by Bart De Pontieu, the IRIS science lead at Lockheed Martin in California).
High-speed jets
Artist’s impression of the solar wind from the sun (left) interacting with Earth’s magnetosphere (right). Credit: NASA
How does the solar wind — that constant stream of charged particles that sometimes cause aurora on Earth — come to be? IRIS spotted high-speed jets of material moving faster than ever observed, 90 miles (145 kilometers) a second. Since these jets are emerging in spots where the magnetic field is weaker (called coronal holes), scientists suspect this could be a source of the solar wind since the particles are thought to originate from there. The paper is here (led by Hui Tian at the Harvard-Smithsonian Center for Astrophysics in Massachusetts.)
Nanoflares
A solar filament erupts with a coronal mass ejection in this image captured by NASA’s Solar Dynamics Observatory in August 2012. Credit: NASA’s GSFC, SDO AIA Team
Those solar flares the Sun throws off happen when magnetic field lines cross and then snap back into place, flinging particles into space. Nanoflares could do the same thing to heat up the corona, and that’s something else that IRIS is examining. The paper is here (led by Paola Testa, at the Harvard-Smithsonian Center for Astrophysics.)
Structures and more
And here is the transition region in glorious high-definition. Improving on data from the Skylab space station in the 1970s (bottom of video), you can see all sorts of mini-structures on the Sun. The more we learn about these 2,000-mile (3,220-km) objects, the better we’ll understand how heating moves through the Sun. The paper is here (led by Viggo Hansteen, at the University of Oslo in Norway.)
Artist's conception of one of the Solar TErrestrial RElations Observatory (STEREO) spacecraft. Credit: NASA
A NASA spacecraft has been out of radio contact for about two weeks, but the agency is still holding out hopes for a rescue. One of the STEREO (Solar TErrestrial RElations Observatory) spacecraft stopped phoning home to Earth on Oct. 1 “immediately after a planned reset of the spacecraft”, NASA said in an update last week.
If the STEREO-Behind spacecraft can’t be recovered, this could cause a data gap in the mission next year — which is unique because it looks at the far side of the Sun. On the website, NASA didn’t say how badly solar weather forecasts are affected, but in other materials they have said both STEREO spacecraft are a crucial part of this work.
STEREO’s pair of satellites (STEREO-Ahead and STEREO-Behind) aim to better map Sun eruptions (known as “coronal mass ejections”) whose charged particles can disrupt satellite communications during solar storms. The mission has been ongoing since 2006 and they’ve viewed the far side of the Sun since 2011. What caused one of them to stop talking to us is unknown, but NASA said recovery attempts are ongoing.
The satellites’ orbits around the Sun are similar to the Earth’s, but one circles a bit faster and the other a bit slower. Next year, geometry (a solar conjunction) means the Sun will block our view of one of the spacecraft at a time. As NASA explained in a July update, “radio receivers on Earth will not be able to distinguish STEREO’s signal from the sun’s radiation.”
This is affecting the mission in two ways. First, there is a period where the antennas on the spacecraft must be repositioned to avoid getting cooked by the Sun. Some data will flow, but it will be in lower resolution. STEREO-Ahead entered this period on Aug. 20, and STEREO-Behind was supposed to send high-resolution data until Dec. 1.
Then there’s a time when each spacecraft will be completely blocked by the Sun. STEREO-Behind was supposed to enter this period from Jan. 22 to March 23, 2015, with its twin still collecting data at this time. But then will come a period where STEREO-Ahead will be out of contact: March 24 to July 7, 2015. If STEREO-Behind can’t fill in for STEREO-Ahead at this time as planned, a data gap could loom.
Lower-resolution data is then expected from STEREO until 2016, when the geometry means the spacecraft can safely reposition their antennas. While these aren’t the only sun-gazing spacecraft — real-time data is still flowing from the Solar Dynamics Observatory (SDO) and the Solar and Heliospheric Observatory (SOHO) — NASA has said that the lower data rate and losing contact with one STEREO spacecraft next year will be difficult for solar forecasting.
“Lack of STEREO observations used in NASA research models will severely limit the forecasting of solar storms throughout the solar system,” the agency said in a July Q&A about the 2015 data losses.
A view of rivers in Montana, USA, from the ISS. Credit: ESA/Luca Parmitano.
A new model suggests that up to half of the water on Earth may be older than the Sun and the rest of the Solar System. The model indicates that much of our planet’s water originated in the molecular cloud that created our Solar System, rather than the disc of material that was orbiting the Sun 4.6 billion years ago.
“Chemistry tells us that Earth received a contribution of water from some source that was very cold – only tens of degrees above absolute zero, while the Sun being substantially hotter has erased this deuterium, or heavy water, fingerprint,” stated Ted Bergin, an astronomy professor at the University of Michigan who participated in the research.
“We let the chemistry evolve for a million years – the typical lifetime of a planet-forming disk – and we found that chemical processes in the disk were inefficient at making heavy water throughout the solar system. What this implies is if the planetary disk didn’t make the water, it inherited it. Consequently, some fraction of the water in our solar system predates the Sun.”
What this could mean is that water would be quite abundant in young solar systems since it doesn’t depend on the chemistry of the planetary disc, but what is in molecular clouds — making it easier, perhaps, for water to arise in planets.
The first Mars observations from NASA’s Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft in three ultraviolet wavelength bands. From left to right, you can see wavelengths that focus on hydrogen, oxygen and reflected sunlight. A composite image is at far right. Credit: Laboratory for Atmospheric and Space Physics /University of Colorado and NASA
Sure is fun to see the Red Planet in different colors! This is what the gases around the Red Planet’s atmosphere look like from NASA’s Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft, which did its first observations on Monday (Sept. 22) — just eight hours after arriving in orbit.
The goal of the spacecraft is to better understand how quickly gases are fleeing the Martian atmosphere, and here you can definitely see a difference between hydrogen (at left) and oxygen (second-to-left). Figuring out how fast the atmosphere escapes could help scientists learn why water appeared to flow freely on the Red Planet’s surface in the distant past.
The hydrogen gas is much lighter and surrounds the planet in a bigger cloud that is so huge it extends beyond the boundaries of the picture at left. The oxygen, which is heavier, is less prone to drifting away and stays closer to the planet. (All images were obtained from an altitude of 22,680 miles or 36,500 kilometers.)
An artist concept of MAVEN in orbit around Mars. (Credit: NASA’s Goddard Spaceflight Center).
It is believed that the Sun’s radiation pushed hydrogen out of the Martian atmosphere in the planet’s past, thinning it over time. A thicker atmosphere would have allowed water to exist in gullies and perhaps even seas or oceans, but today the atmosphere is too thin for liquid water to survive in large quantities on the surface.
MAVEN is in a commissioning phase that will last until early November, although the spacecraft will take a time-out to do observations of Comet Siding Spring upon the object’s closest approach to the planet Oct. 19. So far, NASA does not believe the comet will pose a huge dust threat to the spacecraft, but MAVEN will be maneuvered to minimize exposure just in case.
Solar prominences and filaments on the Sun on September 18, 2014, as seen with a hydrogen alpha filter. Credit and copyright: John Chumack/Galactic Images.
This is a question we are often asked: what is the difference between a coronal mass ejection (CME) and a solar flare? We discussed it in a recent astrophoto post, but today NASA put out a video with amazing graphics that explains it — and visualizes it — extremely well.
“CMEs and solar flares are both explosions that occur on the Sun,” the folks at NASA’s Goddard Spaceflight Center’s Scientific Visualization Studio explain. “Sometimes they occur together, but they are not the same thing.”
CMEs are giant clouds of particles from the Sun hurled out into space, while flares are flashes of light — occurring in various wavelengths — on the Sun.
A low arc, glowing green from excited oxygen, spans the northern sky around 10:30 p.m Central Daylight Time from Duluth, Minn. The Big Dipper is off to the left. Credit: Bob King
Talk of aurora is in the air. Our earlier storytoday by Elizabeth Howell alerted you to the possibility of northern lights. Well, it’s showtime! As of 9:30 p.m. Central Daylight Time, the aurora has been active low in the northern sky.
Subtle pink rays stand above the green arc at 9:35 p.m. CDT. Credit: Bob King
From Duluth, Minn. U.S., a classic green arc low in the northern sky competed with the light of the rising gibbous moon. Once my eyes were dark-adapted, faint parallel rays stood streaked the sky above the arc. NOAA space weather forecasters expect this storm to peak between 1 a.m. CDT and sunrise Friday morning September 12 at a G2or moderate level. Skywatchers across the northern tier of states and southern Canada should see activity across the northern sky. Moonlight will compromise the show, but it rises later each night and dims through the weekend.
The approximate extent of the auroral oval forecast for 11:30 p.m. CDT from Ovation. Credit: NOAA
This is only the start. Things really kick into gear Friday night and Saturday morning when a G3 strong geomagnetic storm is expected from the more direct blast sent our way by the September 10 X1.6 flare. Auroras might be visible as far south as Illinois and Kansas.
We’ll keep you in touch with storm activity by posting regular updates over the next couple days. Including odd hours. Here are some links to check during the night as you wait for the aurora to put in an appearance at your house:
* Ovation oval – shows the approximate extent of the auroral oval that looks like a cap centered on Earth’s geomagnetic pole. During storms, the oval extends south into the northern U.S. and farther.
* Kp index – indicator of magnetic activity high overhead and updated every three hours. A Kp index of “5” means the onset of a minor storm; a Kp of “6”, a moderate storm.
* NOAA space weather forecast
* Advanced Composition Explorer (ACE) satellite plots – The magnetic field direction of the arriving wind from the sun. The topmost graph, plotting Bz, is your friend. When the curve drops into the negative zone that’s good! A prolonged stay at -10 or lower increases the chance of seeing the aurora. Negative numbers indicate a south-pointing magnetic field, which has a greater chance of linking into Earth’s northward-pointing field and wriggling its way past our magnetic defenses and sparking auroras.
