The auroras — aurora borealis near the North Pole, aurora australis near the South Pole — are one of the atmosphere’s most beautiful phenomena, occurring when energetic ions from the sun collide with oxygen and nitrogen in the upper atmosphere, temporarily exciting those particles such that they emit light as they return to their normal states. This particular ribbon of ion activity appears green, the result of excited oxygen atoms at wavelengths near 0.558 millionths of a metre. Other wavelengths produce red, blue, or purple hues (you can see a little bit of red left of center).
This aurora is unique in the sense that it was spotted fairly far away from the South Pole over the southern Indian Ocean, likely as a result of a large ejection of energy that burst from the sun on May 24. The photographer is looking south toward Antarctica, though you can’t see the southernmost continent in the photograph. The ISS orbits at around 354 kilometres, while the aurora was located somewhere in the ionosphere between 96 and 305 kilometres above the planet’s surface.
Popular Science has been a leading source of science, technology and gadget news since 1872. With up-to-the minute latest space news, insightful commentary on the new innovations and concept cars ...if it's new or future technology you'll find it at popsci.com.au.
WW Media - Popular Science © 2010
Technology - DIY - Videos