aurora_animation_011029 Scientists using NASAs Polar spacecraft have recorded the first images of auroras simultaneously brightening the skies over the Earths North and South poles.
Polars Visible Imaging System, a set of three low-light-level cameras, captured the images of the aurora borealis and aurora australis -- the northern and southern lights respectively -- during an Oct. 22 space weather storm caused by a coronal mass ejection of the Sun.
The aurora "movie," really an animation made from the Polar's still photos, spans about a one-hour period of observation. In it, clear aurora ovals can be seen around the North and South poles, mirroring each other as they brighten and expand. The movie also gives a clear view of each auroras inner edge, facing its respective pole, and outer edge, reaching toward the Earths equator.
"Its the first time weve been able to see this dynamic with such clarity and high time resolution," said Nicola Fox, science operations manager for the Polar spacecraft based at NASA's Goddard Space Flight Center. "We were excited that this was a big [aurora] event, and we were able to see the ovals and not just the way the aurora moves and changes."
Fox told SPACE.com that there has been much debate over how mirrored the northern and southern lights are. Only by observing them simultaneously, as in the Polar movie, she said, can their symmetry be seen.
The first recorded observation of mirrored auroras took place about 300 years ago, in September 1770, when Capt. James Cook of the HMS Endeavour noted seeing a phenomena resembling aurora borealis during his exploration of Australia and the South Pacific. At the same time, the book Qing shi gao, a draft history of the Chinese Qing Dynasty reportedly notes an aurora occurring in the northern hemisphere.
Since then, scientists have conducted ground- and air-based aurora studies in both hemispheres, and in the 1980s, NASAs Dynamics Explorer took several photos of the phenomenon. Those pictures, however, were taken at different times and did not have the detail of the new movie, Fox said.
Auroras result from fast-moving particles that become trapped in the Earths magnetic field. Those particles, electrons, plummet into the gases of the upper atmosphere and travel along the invisible lines of the magnetic field, which connect to the Earth near its north and south poles. They then excite nitrogen and oxygen in the atmosphere and produce auroras in rings about 2,500 miles in diameter around each pole.
The Polar spacecraft was launched in Feb. 1996 to study the aurora, as well as the radiation belts, and other phenomena in the space around Earth.
advertisement
