WEEKEND AURORA WATCH: Earth is moving through a stream of solar wind flowing from a hole in the sun's atmosphere. First contact with the gaseous material on May 20th sparked a G1-class geomagnetic storm and auroras across northern-tier US states from Maine to Washington. More storms are possible on May 21st as solar wind speeds remain elevated above 600 km/s. Free: Aurora Alerts
SOLAR WIND SUMMONS "STEVE": During this Saturday morning's solar wind storm, photographer Harlan Thomas stationed himself among the Hoodoos in the badlands of Alberta, Canada. He hoped to catch a display of auroras. This is what he saw:
"Steve appeared!" says Thomas. "I photographed him behind the silhouettes of the Hoodoos alongside Jupiter and a green picket fence aurora."
"Steve" is the purple arc bisecting the sky. For many years, northern sky watchers have reported this luminous form occasionally dancing among regular auroras. It was widely called a "proton arc" until researchers pointed out that protons probably had nothing to do with it. So members of the Alberta Aurora Chasers group gave it a new name: "Steve."
No one fully understands the underlying physics of the purple ribbon. However, one of the European Space Agency's Swarm satellites recently flew overhead while Steve was active, providing some clues.
This ESA video shows Swarm satellites orbiting above ground-based aurora imagers: more
"As the satellite flew straight though 'Steve,' data from the electric field instrument showed very clear changes," reports Eric Donovan from the University of Calgary. "The temperature 300 km above Earth's surface jumped by 3000°C and the data revealed a 25 km-wide ribbon of gas flowing westwards at about 6 km/s compared to a speed of about 10 m/s either side of the ribbon."
Steve's visit to Alberta on May 20, 2017, coincided with another exotic auroral form: the green "picket fence." These vertical rays are thought to trace lines of magnetic force connecting Earth to space. Luminous green columns show where beams of energetic particles are being guided toward Earth's upper atmosphere by magnetic fields.
Both Steve and the picket fence are filamentary structures associated with beams or ribbons of gas. Coincidence? Hardly. Pictures of the two phenomena show that they often appear together. Consider it another clue.
This is the 2nd time in three nights Thomas has seen Steve. "He also spent 15 minutes with me on May 17th," Thomas says. More visitations could be in the offing this weekend as the solar wind continues to blow. Stay tuned.
Realtime "Steve" Photo Gallery
QUADRUPLE GREEN FLASH: Imagine watching the sun set from a Pacific beach. The fiery disk sinks below the waves, and just before it disappears, a fragment of sun appears to flutter into the air--announced by a flash of green light. Now imagine this happening four times in a row. It happened in San Francisco yesterday when photographer Mila Zinkova witnessed a quadruple green flash:
"Last night's sunset produced some unusual green flashes," says Zinkova. "They were unusual because they lasted a second or two longer than they usually do and because at one point there were four green flashes at once."
Ordinary green flashes rely on a mirage to magnify tiny differences in the atmospheric refraction of red and green light. In this case, temperature gradients above the water produced a complex mirage and, not one, but four flashes. Zinkova's complete video of the event is a must-see.
Realtime Space Weather Photo Gallery
THIS PENDANT HAS TOUCHED SPACE: The radiation monitoring program of Earth to Sky Calculus receives no support from corporate sponsors or government grants. Instead, we are crowd-funded. Or, to be more precise, bling-funded:
To raise money for more cosmic ray balloon flights, on May 6th the students launched a payload of these Northern Lights pendants to the top of Earth's atmosphere. You can have one for $79.95. Each piece of space jewelry comes with a greeting card showing the item in flight and telling the story of its journey to the stratosphere and back. They make great birthday and belated Mother's Day gifts.
More far-out gifts may be found in the Earth to Sky Store. All proceeds support atmospheric radiation monitoring and hands-on STEM education.