SOLAR WIND, INCOMING: A minor stream of solar wind is heading for Earth. ETA: April 1st. The gaseous material is flowing from a relatively small hole in the sun's atmosphere, now facing our planet. Arctic auroras are likely when the solar wind arrives. Aurora alerts: SMS Text.
RED AURORAS OVER FLORIDA (AND ELSEWHERE): This hasn't happened in nearly 20 years. On March 24th, auroras descended all the way to Florida. Bill Williams photographed their red glow from the Chiefland Astro Village:
What in the world? Normally, we have a very dark horizon looking out over the Suwannee River Basin and Gulf of Mexico," says Williams. "But my 26-minute exposure taken to capture the Winter Milky Way showed an unusual red glow."
"The mystery was solved the next day as Spaceweather.com described a severe geomagnetic storm well-seen in the U.S. As far as I know, at 29.4 degrees north latitude, we are the farthest south this aurora has been witnessed, and is the first I have seen here in Florida since 2003 and 1989!"
Most auroras are green, yet when auroras spread to low latitudes, the sightings are almost always red. There's a simple reason. Ordinary green auroras come from oxygen atoms about 150 km above Earth's surface. Red auroras are also caused by oxygen, but much higher up, between 150 km and 500 km.
This picture taken the same night by Dean Cosgrove of Curtis, Nebraska, (+40.6N) nicely illustrates the red-on-green altitude structure:
From far-south places like Florida, the greens are eclipsed by the northern horizon, leaving the higher reds to dominate the display.
Other notable sightings of low-latitude red auroras during last week's storm include New Mexico (+32.8N), North Carolina (+36.5N), Colorado (+40.4N), and California (+39.7N).
Did *you* see red? Submit your photos here. Aurora alerts: SMS Text.
Note: Unrelated to auroras, another red glow called "airglow" can also be seen sometimes at low latitudes. Indeed, on any other night, airglow would be a leading explanation for what Williams photographed. But on March 24, 2023, during an extreme geomagnetic storm, with other red auroras being seen only a few degrees away, auroras are the most likely explanation.
Realtime Aurora Photo Gallery
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AURORA DUNES SEEN DURING EXTREME STORM: Lots of unusual things were seen during last week's extreme geomagnetic storm. Alan Dyer of Gleichen, Alberta, photographed one of them, shown here in a deep twilight photo at te onsett of the storm:
"I captured some 'aurora dunes,'" Dyer says. "They are the horizontal green ripples to the left of Venus and the Moon."
Aurora dunes are a recently identified form of Northern Lights named after their resemblence to ripples in desert sand. Researchers first explained them in a paper published only a few years ago. The dunes are a "mesospheric bore," a type of atmospheric gravity wave that springs up from Earth's surface and gets caught in a thermal waveguide ~100 km high. When solar wind particles rain down on the bore, they illuminate its rippling structure.
Sky watchers in the Arctic have been seeing dunes for years without understanding what they were. A breakthrough came on Oct. 7, 2018, when multiple groups photographed dunes from widely separated locations in Finland. Triangulation revealed the dunes to be ~100 km high with a pure, monochromatic wavelength of about 45 km.
This is a new field of study with potential for discovery. Monitoring aurora dunes may reveal previously hidden waves and waveguides at the boundary between Earth and space. If you see any, submit your photos here.
more images: from Michele Sadauskas of Glidden, WI
Realtime Aurora Photo Gallery
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SOLAR ECLIPSE CRYSTAL PYRAMID: On Aug. 21, 2017, during the Great American Solar Eclipse, the students of Earth to Sky Calculus launched 11 space weather balloons from the path of totality. The armada soared into the stratosphere, touching the shadow of the Moon more than 100,000 feet above Earth's surface. This pyramid hitched a ride:
You can have it for $159.95. With the sun, Earth, and Moon perfectly aligned, the faces of the 5-sided crystal caught the reflection of the eclipsed sun. Watch the video! The pyramid comes with a gift card showing the crystal floating at the top of Earth's atmosphere and passing through the Moon's shadow. The interior of the card tells the story of the flight and confirms that this gift has been to the edge of space and back again.
Far Out Gifts: Earth to Sky Store
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