Astronomy Picture of the Day

Explanation: Did you see an aurora over the past two nights? Many people who don't live in Earth's far north did. Reports of aurora came in not only from northern locales in the USA as Alaska, but as far south as Texas and Arizona. A huge auroral oval extended over Europe and Asia, too. Pictured, an impressively red aurora was captured last night near the town of Cáceres in central Spain. Aurorae were also reported in parts of southern Spain. The aurorae resulted from a strong Coronal Mass Event (CME) that occurred on the Sun a few days ago. Particles from the CME crossed the inner Solar System before colliding with the Earth's magnetosphere. From there, electrons and protons spiraled down the Earth's northern magnetic field lines and collided with oxygen and nitrogen in Earth's atmosphere, causing picturesque auroral glows. Our unusually active Sun may provide future opportunities to see the northern lights in southern skies.