Is it "auroras" or "aurorae"? The dictionary prefers the former, but either way, there was a multiplicity of auroral awesomeness this weekend — thanks to a solar storm that swept past Earth's magnetic field over the weekend. During the past few days, we've shown off a few stunning images from Norway and Canada, and there's a new crop to share today.
First, a little explanation for what you're looking at:
Auroral lights arise when electrically charged particles from the sun interact with atoms and ions high up in Earth's atmosphere, 60 to 200 miles up. The interaction sets off emissions in wavelengths ranging from blue, to green (the most common color), to red. The colors depend on the energy of the particles in question. To get the full story on that, check out the explanations from the "Causes of Color" website and the University of Alaska at Fairbanks.
This weekend's auroras were particularly bright because of a strong solar outburst that occurred on Thursday. There's an interval between the outburst and the displays because the particles that are ejected from the sun travel at far less than the speed of light. But they're still pretty speedy — the velocity is on the order of a million miles an hour.
Solar outbursts, known more formally as coronal mass ejections or CMEs, have the potential to disrupt electrical grids or satellite communications. There could be radiation effects on astronauts in orbit or passengers on high-altitude, pole-traversing airplane flights. Thursday's outburst dealt Earth's magnetic field a glancing blow, and no significant negative impact has been reported. However, an even stronger CME is currently on its way toward Earth and may force the rerouting of polar flights. Once again, electric-grid managers and satellite operators will be on alert, as will aurora-watchers.
Observers in northern latitudes can look forward to enhanced auroras over the next couple of nights — and the rest of us can look forward to more images like these:
More great auroral views:
- Northern lights go way, way south
- Speed through Lapland's lights
- Beautiful blasts from solar storms
- Get a video view of Canada's aurora
- Slideshow: The best of the northern lights
- Cosmic Log's auroral archive
Alan Boyle is msnbc.com's science editor. Connect with the Cosmic Log community by "liking" the log's Facebook page, following @b0yle on Twitter or adding Cosmic Log's Google+ page to your circle. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for other worlds.