SpaceWeather.com Archive — Thu, Oct 19, 2023

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POSSIBLE CME IMPACT (UPDATED): Solar wind data from NOAA's DSCOVR spacecraft suggest that a CME may have grazed Earth's magnetic field midday on Oct. 18th. It could be the early arrival of a CME expected today--or a previously unrecognized CME taking us by surprise. Either way, it sparked naked-eye auroras over parts of Canada and Norway, and very faint photographic auroras as far south as Nebraska. Aurora alerts: SMS Text

A PURE SINE WAVE IN THE MAGNETOSPHERE: In a quiet room, you can hear a pin drop. Norwegian citizen scientist Rob Stammes just heard a pin drop on Earth's magnetic field.

"It was very quiet when it happened," says Stammes, who runs a space weather observatory in Lofoten, Norway. On Oct. 17th, his magnetometer was monitoring Earth's magnetic field as it does every night, and the instrument's needle had settled itself into a straight line, indicating very low geomagnetic activity. Suddenly, Earth's magnetic field began to ring.

"A very stable ~25 second magnetic oscillation appeared in my recordings, and lasted for more than 20 minutes," he says. "It was fantastic to see the magnetic field swing back and forth by about 0.1 degrees, peak to peak."

This kind of pure tone is rare, but it has happened before. Researchers call it a "pulsation continuous" -- or "Pc" for short. Pc waves are classified into 5 types depending on their period. The waves Stammes caught fall into category Pc3.

The "pin dropping" was a gentle gust of solar wind. Imagine blowing across a piece of paper, making it flutter with your breath. The solar wind can have a similar effect Earth's magnetic field. Pc3 waves are essentially flutters propagating down the flanks of our planet's magnetosphere excited by the breath of the sun.

A NASA animation of waves fluttering down the sides of Earth's magnetosphere [more]

Stammes is a longtime observer of Pc waves. Usually he catches them during Solar Minimum when "the room is quiet" for months at a time. "Recording one now so close to Solar Max is unexpected," he says. "Lately, my magnetometer traces have been too noisy for such delicate waves--so it came a surprise!"

Pc3 waves, which can only be heard in moments of quiet, can also bring the quiet to an end. The oscillations sometimes flow all the way around Earth's magnetic field and cause a "tearing instability" in our planet's magnetic tail. This, in turn, sets the stage for magnetic reconnection and geomagnetic storms.

That didn't happen on Oct. 17th, though. The pin dropped, the magnetosphere rang, and quiet resumed. Stammes is already listening for more. Stay tuned!

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HANDMADE ANNULAR SOLAR ECLIPSE PENDANT: This pendant has touched the shadow of the Moon. The students of Earth to Sky Calculus launched it to the stratosphere on Oct. 14, 2023, during the annular solar eclipse. The handmade pendant was 78,500 feet high when the Moon's shadow arrived and wrapped it in a cool twilight-like darkness:

You can have it for $129.95. The pendant left Earth from Nevada's Valley of the Moon, a remote area filled with the scent of sage and herds of wild horses. Indeed, no fewer than three mustang families approached the launch team during the eclipse to see what was going on. It was a magical experience.

The students are selling space pendants to pay the helium bill for their cosmic ray ballooning program. Each one comes with a greeting card showing the jewelry in flight and telling the story of its trip to the stratosphere and back again.