SOLAR WIND, INCOMING: A wide hole in the sun’s atmosphere is spewing a fan-shaped stream of solar wind toward Earth. NASA’s Solar Dynamics Observatory photographed the canyon-like structure on Jan. 14th:
This is a “coronal hole” (CH)–a region where the sun’s magnetic field opens up and allows solar wind to escape. Material is flowing from this coronal hole at speeds exceeding 600 km/s (1.3 million mph). The high-speed stream could spark G1-class geomagnetic storms when it arrives on Jan. 18-19. Arctic sky watchers, mark your calendars!