Auroras happen when ions in the solar wind collide with atoms of oxygen and nitrogen in the upper atmosphere. The atoms are excited by these collisions, and they typically emit light as they return to their original energy level. The light creates the aurora that we see. The most commonly observed color of aurora is green, caused by light emitted by excited oxygen atoms at wavelengths centered at 0.558 micrometers, or millionths of a meter. (Visible light is reflected from healthy (green) plant leaves at approximately the same wavelength.) Red aurora are generated by light emitted at a longer wavelength (0.630 micrometers), and other colors such as blue and purple are also sometimes observed
As solar activity ramps up again, more sights light this are lighting up the skies over the South Pole.
Like its more well known cousin in our northern hemisphere "aurora borealis", this "aurora australis" forms over the southern polar region.
This out of world cool photo comes from the International Space Station crew on May 29, 2010.
So what gives with the green color? NASA says the differences in color are due to "excited" oxygen atoms near the .558 micrometers wavelength. This is actually the most common color for most auroras though we do see others in red, bluish and purple tones when associated with longer wavelengths.
Scientists say the Sun is slowly awakening out of a prolonged "solar minimum" period known for a lack of sunspots (think solar storms). As sunspots/solar activity ramps up - more light displays are likely to come possibly far enough south to be seen in Northern California during the next 12 year cycle. The downside, strong solar storms could bring troubles for satellites and even the ISS itself. Something our world of 3G/4G, ATMs and power grids may not appreciate much in the coming years.
- Rob Mayeda
Equally as excited for next year's "Green Lantern" movie starring Ryan Reynolds, which is what he thought this photo was originally intended for until he saw the NASA logo.