ARCTIC AURORA WATCH: Around the Arctic Circle, localized geomagnetic storming is possible on Dec. 17th and 18th as Earth passes through a minor stream of solar wind. This event will probably not register on NOAA storm scales because those scales measure global, not local activity. Locally, however, there could be some auroras around the poles even as the planetary K-index remains low. Free: Space Weather Alerts
A BIG CORONAL HOLE TURNS TOWARD EARTH: For the third month in a row, a large hole in the sun's atmosphere is turning toward Earth. NASA's Solar Dynamics Observatory photographed the yawning structure on Dec. 16th:
This is the same coronal hole that lashed Earth's magnetosphere with solar wind on Oct. 25-28 and again on Nov. 23-26. It is spinning around with the sun, strobing Earth lighthouse-style every ~27 days. The last two times we experienced its solar wind, intermittant G1-class geomagnetic storms and bright auroras were observed in the Arctic. A repeat performance is likely when the solar wind returns on Dec. 20-22.
A GREEN FLASH OVER DRY LAND: Seaside photographers have a special fondness for the sunset. It's the time of day for the green flash--a split-second pulse of verdant light that signals the disappearance of the sun beneath the ocean waves. But the sea is not always required. Yesterday in Treviso, Italy, Enrico Finotto was looking across dry land when he witnessed this magnificent green flash:
"It was a complete surprise," says Finotto.
Atmospheric optics expert Les Cowley explains what happened: "This is a mock-mirage green flash produced by light rays bending as they cross a temperature inversion layer. Such flashes can happen over land as well as the sea. We see more flashes over the sea because the sea horizon is not obscured by hills or buildings. But land flashes can be just as spectacular."
Moreover, dry land offers an advantage that the sea does not. "Over land you might also see a flash twice!" continues Cowley. "I saw once one from our garden, ran indoors and upstairs to see a repeat performance a few seconds later. Try this on a hill slope but be careful, it can be the stuff of heart attacks!"
Realtime Space Weather Photo Gallery
ORDER NOW FOR CHRISTMAS DELIVERY: It's out of this world: the Sirius Space Pendant. To raise money for their space weather ballooning program, the students of Earth to Sky Calculus have flown 3 dozen pendants to the edge of space–and you can have one for $79.95. The pendant comes with a greeting card showing the jewelry in flight and certifying that it has been to the stratosphere and back again.
The pendants flew to the edge of space on Nov. 20, 2016, alongside an array of cosmic radiation sensors. During the flight, the sensors measured the highest radiation levels in the history of our monitoring program. After the balloon exploded, the payload parachuted back to Earth, landing in the snowy San Antonio mountains north of Tonopah, Nevada, where a student team recovered it on Nov. 22nd.
The research of Earth to Sky Calculus is not supported by government grants or corporate donations. Instead, we are entirely crowd-funded. Proceeds from the sale of items like the Sirius Pendant go right back into cutting-edge student research. More edge of space Christmas gifts may be found in the Earth to Sky Store.
Realtime Airglow Photo Gallery