UPDATE: The CME arrived last night, but was weaker than expected. Solar storm conditions are not likely into Sunday night despite clearing skies locally. It appears highly unlikely any significant display will occur anywhere in the United States Sunday night.
For the second time in a month, an outburst of auroras could dazzle nighttime sky watchers as we head into Halloween. This particular display could be even better than the first.
Like people, our sun is (at times) peppered with freckles. These freckles, called sunspots, are boiling cauldrons of concentrated energy just waiting to erupt. When conditions are just right, these sunspots can “pop”. This of it like a little sun burp, spewing out enormous plumes of highly energetic plasma into space.
Many times, these burps of energy fly out away from the sun never to encounter anything worth mentioning. Other times, these “coronal mass ejections,”, or CME for short, encounter objects floating around in space. That’s where you and I come in.
This week’s CME is forecast to directly impact Earth, setting off a cascade of radio and magnetic disturbances that trigger auroras.
When this energy strikes Earth’s magnetic field, it triggers a collision and reaction with atoms in our ionosphere that set off a colorful glow easily visible in the night sky.
FUN FACT: The color you see is the direct result of the altitude & makeup of the atoms involved. For example, lower level oxygen gives off the familiar green color. Oxygen at higher altitudes can produce red auroras. Nitrogen can produce hues of blue, red and purple.
Now, auroras are visible from Earth almost every night. You just have to live at the poles to see them. Getting the Northern Lights to spill southward in latitude into the United States takes a particularly strong solar flare. This one seems to fit that bill with forecast calling for a G3 level storm (like hurricanes or tornadoes, it runs from G0-G5 with the bigger the number the more intense the display.
Should a G3 storm indeed occur, it would allow auroras to spill into the New England, the Great Lakes and even as far south as the Ohio Valley. But there’s a catch to all this. Forecasting these CME’s is extremely difficult, not only timing the arrival of impact but predicting the magnitude of the display.
My time working in Alaska involved many “busted” aurora outbreaks, both not happening when predicted and even happening when no one thought they would. Their forecasting is fickle and as of this writing, the CME has not yet hit Earth. Forecasts suggest it could occur at any moment, perhaps even into the week hours of Halloween. If/when it hits Earth, aurora displays will build quickly in the coming hours. Should the impact arrive tonight, Saturday night would prove to be the best time to view.
Strong displays typically wane the following day/night, but can still produce noteworthy auroras the following night. It’s all about timing now.
WNY residents have another problem, and it’s big one. Should this display get cranking Saturday night, you likely won’t see it. Abundant cloud cover will prevent all but the luckiest and most patient sky watchers from seeing anything. We do, however, predict clouds will break somewhat into Sunday night.
If this CME arrives late, that could give us at least some opportunity to see the show. No rush, CME. Take your time.