GEOMAGNETIC STORM UNDERWAY: Auroras are dancing around the Arctic Circle on Oct. 14th as Earth slowly exits the magnetized wake of a CME that struck two days ago. Currently, geomagnetic storms are flickering between categories G1 and G2. Mia Stålnacke sends this picture from Kiruna, Sweden:
“Last night was amazing,” she says. “Before it was even really dark the aurora was dancing wildly and bright! This shot shows the display over lake Ala Lombolo, which is starting to freeze over.”
WHAT’S NEXT? On Oct. 15th, another disturbance is expected to hit Earth’s magnetic field. This time it’s coming from a coronal hole–a gap in the sun’s atmosphere from which solar wind flows:
NASA’s Solar Dynamics Observatory took this picture on Oct. 13th. It shows the dark coronal hole pointing almost directly at Earth. At the leading edge of the emerging solar wind stream is a co-rotating interaction region (CIR)–that is, a transition zone between slow- and fast-moving solar wind. Shock waves and density gradients in CIRs often go a good job sparking auroras, so when it arrives on Oct. 15th polar auroras are likely. Stay tuned for pretty pictures. Free: Aurora Alerts.