Slow-motion Solar Flare and CME

June 13, 2022: Growing sunspot AR3032 exploded on June 13th (0407 UT), producing an M3-class solar flare that lasted nearly 8 hours from beginning to end. NASA’s Solar Dynamics Observatory recorded the slow-motion blast:

Extreme ultraviolet radiation from the flare ionized the top of Earth’s atmosphere, causing a shortwave radio blackout over Japan and southeast Asia: blackout map. Radio operators in the area may have noticed unusual propagation effects at frequencies below 30 MHz for more than an hour after the flare’s peak.

Also, the explosion hurled a magnificent CME into space, according to coronagraphs onboard the Solar and Heliospheric Observatory (SOHO). Click to set the scene in motion:

NOAA analysts have determined that the CME will pass near Earth later this week, possibly delivering a glancing blow to our planet’s magnetosphere. Their simulation suggests an arrival time of 0900 UT on June 15th. Minor G1-class geomagnetic storms are likely if and when the CME makes contact. Solar flare alerts: SMS Text.

Mapping a Magnetic Superstorm

June 13, 2022: Researchers have mapped the best and worst places in the USA to be during a severe geomagnetic storm. For residents of some big cities, the news is not good.

“Resistive structures in the crust and mantle of the Earth make cities along the east coast of the USA especially vulnerable to geomagnetic storms,” says Jeffrey Love of the US Geological Survey (USGS), who led the study. “Hazards are greatest for power systems serving Boston, New York, Philadelphia, Baltimore, and Washington, DC, – a megalopolis of over 50 million people.”

Above: Resistive structures in the crust of the Earth measured by the Earthscope project. Credit: Kelbert et al. (2019) [more]

These conclusions are based on a new study of the biggest geomagnetic storm of the Space Age–the Great Québec Blackout of March 13, 1989. Millions of Quebecois spent a long winter night without lights or heat after a pair of CMEs hammered Earth’s magnetic field. The Hydro-Québec power grid was down for more than 9 hours.

What would happen if the same geomagnetic storm struck again? That’s what Love’s team wanted to find out. They combined old measurements of magnetic activity during the 1989 storm with new measurements of Earth’s crust to pinpoint the hazard zones.

At this point, it may be useful to review what happens during a geomagnetic storm. When a CME hits Earth’s magnetic field, our magnetic field vibrates. If you had a sensitive-enough compass, you could see the needle quivering. Next, because of Faraday’s Law, electrical currents begin to flow through conductors. Power lines, pipes, even rocks conduct these geomagnetically induced currents (GICs). Together, Earth and power lines form an electrical circuit; if too much current flows into the power grid it can cause a blackout.

Above: During a geomagnetic storm, geomagnetically induced current (GIC) flows through power lines and the Earth itself. Credit: GAO

In 1989 researchers didn’t know much about the Earth-half of the circuit. That has changed. In 2006, the Earthscope project began sounding our planet’s crust to determine the 3D electrical properties of deep rock. It turns out, there are huge variations in conductivity from place to place. The type of rock a city sits on determines how vulnerable it is to geomagnetic storms.

In retrospect, Québec was especially vulnerable. The province sits on an expanse of Precambrian igneous rock that does a poor job conducting electricity. When the March 13th CMEs arrived, storm currents found a more attractive path in the high-voltage transmission lines of Hydro-Québec. Unusual frequencies began to flow through the lines, transformers overheated and circuit breakers tripped.

Assuming that the Québec storm was underway again, Love’s team mapped electric fields around much of North America. Measured in units of Volts per kilometer (V/km), these fields predict how much current will be pushed through wires at ground level. The higher the value, the bigger the hazard.

Above: If you live near an orange dot you might be in trouble during a geomagnetic superstorm. The color-coded dots represent peak geoelectric field amplitudes. Credit: Love et al (2022). [movie]

“Peak 1-min-resolution geoelectric field amplitudes ranged from 21.66 V/km in Maine and 19.02 V/km in Virginia to <0.02 V/km in Idaho,” says Love. “Our maps show where utility companies might concentrate their efforts to mitigate the impacts of future magnetic superstorms.”

With Solar Cycle 25 ramping up to a new Solar Maximum expected in 2025, the hazard maps are coming not a moment too soon.

You can read Love et al.’s original research in the May 2022 edition of the research journal Space Weather. Click here.

Rare Early Morning Sky Show

June 12, 2022: How many planets can you see before breakfast? Tom Harradine of Brisbane, Australia, woke up early Thursday morning and found the entire solar system sprawled across the dawn sky:

“This might not be a very spectacular image, but it is relatively unique,” says Harradine. “Captured here in a single photograph are all the major planets of our Solar System, spanning about 90° across the eastern dawn Brisbane sky. Mercury, Venus, Mars, Jupiter and Saturn can be seen with the unaided eye. Uranus and Neptune require binoculars.”

This is the first time since December 2004 that the five naked-eye planets have appeared together in this way. They are arrayed in order of distance from the sun: Mercury, Venus, Mars, Jupiter and Saturn. In the mornings ahead, Mercury will climb higher and brighten, making the group even easier to see.

Dates of special interest include June 16th when Mercury is farthest from the sun and June 21st through 26th when the Moon hops from planet to planet, producing a series of early morning conjunctions. Set your alarm for dawn and enjoy the show! Sky maps: today, June 21, 22, 23, 24, 25, 26.

more images: from Paolo Bardelli of Sumirago (Varese), Italy; from James Glucksman of Kakanui, New Zealand; from Bob Beal of Washington, Utah; from Noeleen Lowndes of Gold Coast Qld Australia; from Gary Dowdle of Fort Davis, Texas;

Reversed Polarity Sunspot

June 2, 2022: A new and unusual sunspot has emerged in the sun’s southern hemisphere: AR3027. It is a reversed-polarity sunspot; its magnetic field is backwards.

Above: A magnetic map of the sun’s surface from NASA’s Solar Dynamics Observatory.

According to Hale’s Law, Solar Cycle 25 sunspots in the sun’s southern hemisphere should have a +/- polarity. That’s positive on the left, negative on the right. However, the magnetogram above shows the opposite. Sunspot AR3027 is breaking the law!

Studies show that about 3% of all sunspots violate Hale’s Law. In some ways, reversed polarity sunspots act totally normal. For instance, they have the same lifespan and tend to be about the same size as normal sunspots.

In one key way they are different: According to a 1982 survey by Frances Tang of the Big Bear Solar Observatory, reversed polarity sunspots are more than twice as likely to develop complex magnetic fields, in which + and – are mixed together. Reversed polarity sunspots are therefore more likely to explode.

AR3027 could become a source of flares in the days ahead. Stay tuned! Solar flare alerts: SMS Text.

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The Tau Herculid Meteor Shower — Possible Outburst

May 25, 2022: In late 1995, Comet 73P/Schwassmann-Wachmann 3 exploded. Almost 30 years later, some of the debris might hit Earth.

Above: NASA images of Comet 73P still crumbling years after its initial breakup. [more]

Multiple forecasters agree that a meteor shower could erupt on May 31, 2022, when Earth runs into one or more debris streams from Comet 73P. The display could be as intense as a meteor storm (1000 or more meteors per hour) or as weak as nothing at all. No one knows how much debris is inside the approaching streams, so meteor rates are hard to estimate.

Whatever happens, people in North America are in a good position to see it. Almost the entire continent will be in Moon-free darkness when the shower peaks. Maximum activity is expected around 1:00 am Eastern Daylight Time (05:00 UT) on Tuesday morning, May 31st. The shower’s radiant (the point from which all meteors stream) will be almost straight above Baja California.

Above: Altitude contours for the shower’s radiant. Baja California is favored with zenith observing geometry. Image credit: Josselin Desmars (IMCCE/IPSA) [more]

This isn’t the first time Earth has sampled debris from Comet 73P. In 1930, at least a handful of meteors were observed shortly after the comet’s discovery by German astronomers. The meteors emerged from a radiant near 4th magnitude star tau Herculis, so the shower has since been called “the tau Herculid meteor shower.” NASA cameras also detected minor tau Herculid activity in 2011 and 2017.

Based on past performance, the tau Herculids seem unlikely to produce a good show. For nearly a century the shower has been a dud. The X-factor this year is fresh material from the comet’s catastrophic breakup. If the new meteoroids reach Earth–and that is a big IF–shooting stars will fly from a point near the bright star Arcturus in the constellation Bootes. Here is a sky map to help you find it.

To learn more about the tau Herculid meteor shower, we recommend this comprehensive paper by Joe Rao, a lecturer at the Hayden Planetarium in New York. Also, a new analysis by Jérémie Vaubaillon of the Institute for Celestial Mechanics and Computation of Ephemerides in Paris raises the possibility of two additional outbursts on May 31st resulting from debris shed by Comet 73P in the years 1892 and 1897.

It all adds up to a date with the night sky at the end of the month. Don’t miss it!

A Mixed Up Sunspot

May 10, 2022: Sunspot AR3006 is having an identity crisis. It is supposed to have a +/- magnetic field. Mostly it does. But deep inside the sunspot’s primary core, the polarity is opposite: -/+. Note the circled region in this magnetic map of the sunspot from NASA’s Solar Dynamics Observatory:

The mixture of magnetic polarities makes this sunspot interesting and dangerous. When opposite polarities bump together, it can light the fuse of magnetic reconnection–the explosive power source of solar flares. If AR3006 flares today, it will be geoeffective. The sunspot is directly facing Earth.

Update: The sunspot *did* flare today. An X1.5 class explosion on May 10th (1355 UT) caused a radio backout over the Atlantic Ocean and may have hurled a complicated CME toward Earth. Solar flare alerts: SMS Text

A Tiger ELVE over Texas

May 2, 2022: For a few milliseconds last Thursday night, an enormous (100 km wide) red ring of light appeared over west Texas. Thomas Ashcraft photographed it from across the state line in New Mexico:

This is an “ELVE”–short for Emissions of Light and Very Low Frequency Perturbations due to Electromagnetic Pulse Sources. It’s a rare species of sprite discovered in 1990 by cameras onboard the space shuttle. Ashcraft may have just taken the best ever picture of one from the ground.

“The ELVE was generated by a super-strong lightning stroke that occurred over west Texas near the town of Borger at April 28 2022 0439:10.5326 UT,” says Ashcraft. “Note also the sprite elements at the bottom of the ELVE.”

The lightning bolt was so strong, it generated an intense electromagnetic pulse (EMP). The red ring marks the spot where the EMP hit Earth’s ionosphere. Normal lightning bolts carry 10 to 30 kilo-ampères of current; this bolt was about 10 times stronger than normal.

Above: A close-up view of the ELVE shows “tiger stripes” and sprites near the center of the ring.

“The lightning stroke that manifested this event registered on VLF radios at least as far away as Germany,” notes Ashcraft. “You can actually hear the lightning stroke in my video.”

Bonus: This is also a Tiger ELVE. Note the linear corrugations across the red ring. These are impressed on the ELVE by gravity waves in the upper atmosphere. Like a tiger, this ELVE has stripes.

Learn more about the history and physics of ELVEs here and here.

Mercury’s Comet-like Tail

April 29, 2022: Planets aren’t supposed to have tails, but Mercury does. Dr. Sebastian Voltmer just photographed it from La Palma in the Canary Islands:

“This is NOT a comet, not even a meteor, but the planet Mercury, which is currently very close to the Pleiades,” says Voltmer. “How is the tail formed? The solar wind and micro-meteorites eject sodium atoms from Mercury’s surface. This creates a yellow-orange tail of sodium gas that is around 24 million kilometers long.”

People around the world have been watching Mercury climb up the evening sky this month. Some of them are probably wondering “why didn’t I see the tail?”

Answer: A special filter is required. “I used a 589 nanometer filter tuned to the yellow glow of sodium,” says Voltmer. Without this kind of sodium filter, Mercury’s tail would be invisible.

Above: Dr. Sebastian Voltmer observing Mercury from La Palma on April 27, 2022. Inset is the 589 nm sodium filter. [video]

Voltmer says the tail is so bright, he could see it in individual 30 second exposures. “I can see some very small changes in shape of the tail,” he says, “and the brightness is slightly increasing.”

The nights ahead are excellent times to catch this phenomenon. On April 29th and 30th, Mercury will glide past the Pleiades star cluster for a fantastic photo-op. Then, on May 1st and 2nd, the crescent Moon joins the show.

“Currently I’m imaging Mercury day by day just after sunset from the Canary Islands,” says Voltmer. Stay tuned for more sodium.

Sky maps: April 29, April 30, May 1, May 2

Dead Sunspot Explodes, Hurls Debris Toward Earth

April 11, 2022: The corpse of old sunspot AR2987 exploded today, April 11, 2022, hurling debris directly toward Earth. NASA’s Solar Dynamics Observatory recorded the eruption:

The S-shaped magnetic filament at the base of the explosion is a classic “sigmoid structure.” Solar magnetic fields often assume this shape just before they explode. One study shows that sigmoid precursors are present in over 50% of CMEs.

Indeed, shortly after the explosion, a full-halo CME emerged from the blast site. Here it is. The CME is expected to reach Earth on April 14th; a new NOAA model pinpoints its arrival time at 1100 UTC. The impact could spark a G2-class geomagnetic storm. Aurora alerts: SMS Text

Surprise Geomagnetic Storm

April 10, 2022: Earth’s magnetic field was supposed to be quiet on April 10th. Instead a strong (G3-class) geomagnetic storm broke out. At the apex of the disturbance, auroras crossed the Canadian border into multiple northern-tier US states. Ron Risman sends this time-lapse movie from Milton, New Hampshire:

“We don’t get to see the aurora all that often in New Hampshire, but this solar cycle so far has been fantastic,” says Risman. Before the show was over, the lights spread west all the way to Washington state.

What caused the storm? The prime suspect is a “canyon of fire” CME, which hit Earth’s magnetic field on April 8th. The impact was weak and, at first, it seemed to have little effect. Geomagnetic unrest increased on April 9th as Earth passed into the CME’s strongly magnetized wake. The arrival of an unrelated solar wind stream on April 10th tipped conditions into G3-category storming.

more images: from Shayne Smith of Charlevoix, Michigan; from Dirk S. Miller of Rice Lake, Wisconsin; from Rocky Raybell of Keller, Washington; from Christy Turner of Calgary, Alberta; from Thomas McCarty of Fairbanks, Alaska; from Ian Griffin of Hoopers Inlet, Otago Peninsula, New Zealand; from Gunjan Sinha of Saskatoon, SK, Canada