One of many items on my “things to do before I die” list, is see a major aurora borealis (Northern Lights) event. I’ve seen a few here in Wisconsin, but they are nothing compared to the beautiful nighttime shows that take place in polar locations like Alaska. Or visit the Southern Hemisphere for a Southern Lights or aurora australis show. (australis is Latin for “of the south”)
What causes the auroras?
Like any nuclear reaction, the thermonuclear reactor that is our Sun emits a steady flow of hot plasma from it’s million-degree outer surface known as solar wind. (Plasma is a gas of free electrons and positions ions – as matter becomes more energetic it goes from solid to liquid to gas to plasma – this is a energy state so hot that the atoms break apart into separate particles). This stream of charged particles flows towards the Earth at about 400km/s (about 15,000 mph) and for the most part, the flows smoothly around the Earth’s protective magnetosphere and continues onward towards space. However, there are occasional disruptions which cause the particles to barrel down towards the Earth. These highly energized particles collide with gas molecules in the upper atmosphere and induces them into an excited energy state. As the gas molecule cools down to it’s original energy state it releases the stunning greens, blues, reds, and whites of the aurora.
While everyone agrees how breathtaking auroras are, there is debate among scientists about the mechanism of these disruptions that cause geomagnetic storms. On Saturday, NASA launched a Delta II rocket carrying five identical probes of the THEMIS mission that will work together to analyze the geomagnetic storms. Not only will the five probes be working on the case, there will a great collaboration between satellites of the European Space Agency’s Cluster mission, the Double Star mission of the Chinese space agency, and 20 ground stations in Alaska and Canada.
Stay tuned for updates on the THEMIS mission, auroras, and how the activity of sun affects our daily lives in the obvious and not so obvious ways.
Interesting factoid: THEMIS stands for Time History of Events and Macroscale Interactions during Substorms. That’s a mouthful, but a simpler factoid behind the mission name is that Themis is the mythological Greek goddess of justice, wisdom, good counsel, and the guardian of oaths.
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Posted by Tim Roth, author of the political blog Think Anew and Act Anew
Sources:
1. Official webpage of NASA’s THEMIS mission”
2. “NASA’s Aurora mission blasts off”, BBC article
3. “Aurora (astronomy)”, Wikipedia entry
