Astronomy Picture of the Day

Explanation: Wind and spaceweather are transformed in this haunting night skyscape. The prairie windmill and colorful auroral display were captured on October 1, from central South Dakota, USA, as a good season for aurora hunters came with longer autumn nights. From green to rarer reddish hues, the northern lights are sparked by the geomagnetic storms caused by solar activity. These extend far above the cloud bank to altitudes well over 100 kilometers, against the backdrop of distant stars in the northern night. Visual double star Mizar, marking the middle of the Big Dipper's handle, is easy to spot at the left edge of the frame. The dipper's North Celestial Pole pointers Merak and Dubhe line up vertically near picture center.