Science
Why are auroras different colors?
Last week, a huge solar flare sent a wave of energetic particles from the Sun surging out through space. Over the weekend, the wave reached Earth, and people around the world enjoyed the sight of unusually vivid aurora in both hemispheres.
While the aurora is normally only visible close to the poles, this weekend it was spotted as far south as Hawaii in the northern hemisphere, and as far north as Mackay in the south.
Got a needle in a haystack image. It disappeared just as fast. I’m still speechless. Aurora in Hawaii pic.twitter.com/HzKVWTHbnIMay 12, 2024
This spectacular spike in auroral activity appears to have ended, but don’t worry if you missed out. The Sun is approaching the peak of its 11-year sunspot cycle, and periods of intense aurora are likely to return over the next year or so.
If you saw the aurora, or any of the photos, you might be wondering what exactly was going on. What makes the glow, and the different colours? The answer is all about atoms, how they get excited – and how they relax.
When electrons meet the atmosphere
The auroras are caused by charged subatomic particles (mostly electrons) smashing into Earth’s atmosphere. These are emitted from the Sun all the time, but there are more during times of greater solar activity.
Most of our atmosphere is protected from the iNFLux of charged particles by Earth’s magnetic field. But near the poles, they can sneak in and wreak havoc.
Earth’s atmosphere is about 20% oxygen and 80% nitrogen, with some trace amounts of other things like water, carbon dioxide (0.04%) and argon.
-
Science1d ago
Al Naslaa rock: Saudi Arabia's enigmatic sandstone block that's split perfectly down the middle
-
Science1d ago
SpaceX Falcon 9 rocket grounded for 2nd time in 2 months following explosive landing failure
-
Science1d ago
James Webb telescope spots 6 enormous 'rogue planets' tumbling through space without a star
-
Science2d ago
Ancient viral genomes plucked from glaciers reveal how pathogens have adapted to Earth's shifting climate
-
Science2d ago
Large patch of the Atlantic Ocean near the equator has been cooling at record speeds — and scientists can't figure out why
-
Science2d ago
Gravitational waves hint at a 'supercool' secret about the Big Bang
-
Science3d ago
200 meteorites on Earth traced to 5 craters on Mars
-
Science4d ago
Scientists collect high-resolution images of the North Star's surface for 1st time