Why would the sky glow red? Aurora. Last week’s solar storms, emanating mostly from active sunspot region 1402, showered particles on the Earth that excited oxygen atoms high in the Earth’s atmosphere. As the excited element’s electrons fell back to their ground state, they emitted a red glow. image credit: Alex Cherney
Were oxygen atoms lower in Earth’s atmosphere excited, the glow would be predominantly green. Pictured above, this high red aurora is visible just above the horizon last week near Flinders, Victoria, Australia. The sky that night, however, also glowed with more familiar but more distant objects, including the central disk of our Milky Way Galaxy on the left, and the neighboring Large and Small Magellanic Cloud galaxies on the right. A time-lapse video highlighting auroras visible that night puts the picturesque scene in context. Why the sky did not also glow green remains unknown.
After chasing it for more than two years I was finally rewarded with two displays of Aurora Australis (Southern lights) within a week visible from Mornington peninsula, not far from Melbourne. The nights were warm an clear and the Moon was not in the sky either – I could not have asked for better conditions.
The red color of this aurora is caused by the charged particles from the Sun exciting oxygen atoms high in the Earth’s atmosphere. Hopefully there will be more to come as Sun’s activity increases in 2012-13.
Being able to photograph it all night I came up with a nice video. The brighter Aurora happened on January 22nd and the smaller one, featured in the middle section, was from January 16th, followed by a rather bright Moonrise.
Images and blog: