THE STORM IS OVER: Arriving hours earlier than expected, a CME hit Earth's magnetic field on April 24th (2307 UT). The impact sparked a brief G1-class geomagnetic storm, stopping short of the stronger G2-class storm in the forecast. The storm is over now and only minor geomagnetic unrest is likely as Earth exits the CME's wake. Aurora alerts: SMS Text.
AURORA 'DUNES' SIGHTED OVER CANADA: Auroras still have the capacity to surprise. On April 16th, Matthew Wheeler, an experienced aurora-watcher in Robson Valley, British Columbia, saw a green glow forming in the north--then he noticed something odd. "Horizontal lines caught my attention," he says. "There appeared to be ripples in the aurora." Six of them are labeled in this 1/2 second exposure:
A video captured by Wheeler shows their dynamics over a 20-minute period: watch it.
These are "dunes," a newly recognized form of aurora named after their resemblence to desert sand dunes. A team of researchers first explained them in a paper published just last year. 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. Have you seen a dune? Submit your photos here.
Realtime Aurora Photo Gallery
Free: Spaceweather.com Newsletter
SOLAR TRANSIT OF THE ISS AND CREW DRAGON: On Saturday, April 24th, SpaceX's Crew Dragon capsule (Endeavour) docked with the International Space Station, delivering 4 new astronauts to the orbiting outpost. An hour later, astrophotographer Thierry Legault caught them racing 27,000 km/h across the face of the sun:
"I photographed the split-second transit about 50 km north of Paris," he says. "The Crew Dragon capsule is on the left between the solar panels."
There are now 11 astronauts onboard the ISS: 6 from NASA, 2 from Russia, 2 from Japan and 1 from the European Space Agency. The crowding with subside on Tuesday when 4 of the astronauts board another SpaceX Crew Dragon capsule (Resilience) and return to Earth.
Realtime Space Weather Photo Gallery
Free: Spaceweather.com Newsletter
MOTHER'S DAY IS MAY 9TH: Are you looking for an out-of-this world Mother's Day gift? Consider this: Every time the students of Earth to Sky Calculus launch a cosmic ray balloon, they include something extra in the payload--something Mom will love:
Every item in the Earth to Sky Store has flown to the edge of space and comes with a greeting card showing the item in flight. The interior of the card tells the story of the gift's journey from launch to landing. Mom-satisfaction guaranteed!
Mother's Day Special: Use coupon code "SPACEMOM" at checkout for a 10% discount. Offer valid from now until Mother's Day (May 9, 2021) .
Far Out Gifts: Earth to Sky Store
All sales support hands-on STEM education
Realtime Aurora Photo Gallery
Free: Spaceweather.com Newsletter