Comet K2 Has Arrived

June 28, 2022: For the past 3 million years, Comet C/2017 K2 (PanSTARRS) has been falling toward the sun–a long, slow journey from the Oort cloud. Finally, it’s here. Austrian astrophotographer Michael Jaeger photographed “Comet K2” entering the inner solar system on June 25th:

“This is a 22-minute exposure with my 16-inch telescope,” says Jaeger. “The comet was about 9th magnitude.”

Comet K2 caused a sensation when it was discovered in 2017. At first, it appeared to be one of the biggest comets in modern history, with a nucleus as much as 160 km wide. Hubble Space Telescope observations have since downsized it to 18 km. That’s still big (typical comet nuclei measure 1 to 3 km), but not a record setter. K2 is comparable in size to Halley’s Comet.

The comet will make its closest approach to Earth (1.8 AU away) on July 14th, brightening to 7th or 8th magnitude. This is too dim to see with the naked eye, but an easy target for backyard telescopes. A good time to look is now before the full Moon of July 13th interferes. Comet K2 may be found high in the midnight sky in the constellation Ophiuchus.

Sky maps: June 29, 30, July 1. Additional resources: current coordinates, 3D orbit, light curve.

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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