Astro Bob: Aurora alert Monday night Oct. 3
Solar blasts are expected to arrive Monday evening and last through Tuesday. To help plan, we've got tips on aurora apps for your phone.
The sun's gone wild. On Monday, Oct. 3, at least seven sunspot groups dotted the solar terrain. The two largest regions, 3110 and 3112, have been busy producing flares — explosions that propel charged clouds of particles in Earth's direction. Region 3112 is the biggest and spottiest and extends for nearly 81,000 miles (130,000 km), more than 10 times the diameter of the Earth.
While Region 3110 is rotating away from us and will soon be on the sun's backside, 3112 is just getting warmed up and may spawn tempestuous space weather for the next couple weeks.
On Monday evening, Oct. 3, through Tuesday night, multiple CMEs will arrive, increasing the odds that the aurora will start early and stay late. So you know, we had a similar forecast last weekend for a G2 storm that sadly never materialized. The aurora can be like that. Sometimes it shows up earlier than expected — when it's still daylight over North America — or hours late. Just be prepared.
Space weather forecasters predict Monday night's moderate G2 storm will begin around 7 p.m. CDT and last through the night. I only wish they'd also forecast clear skies here in northern Minnesota. Skywatchers east and south of me in northern and central Wisconsin will fare better. Maybe the clouds will part on Tuesday evening, when a G1 storm is expected.
During a G2 storm, the aurora is visible as far south as Illinois and Oregon. We have a moon out — just past half — which would diminish a minor storm but not a moderate one. Either way it sets around midnight, setting the stage for a nice show.
Identify in advance a good spot where you can keep an eye on things. That location should have an unobstructed view to the north with no towns or other major sources of light pollution in that direction. To help you find a spot, use this interactive light pollution map . Drag and zoom with your mouse to locate your town, then seek the nearest blue-or-gray-colored area — that's where the darkest skies are.
Check regularly during the night, looking for a pale green glow low in the northern sky. Remember to allow your eyes to adapt to the dark before you decide to stick around or call it quits. Auroras often start slowly and take time to flower like watching a rose bloom in a time-lapse video.
Here are some links you might find helpful:
Current auroral oval
— shows the extent of the aurora. If it's over your region, chances are good you'll see it.
2. Latest space weather forecast — If the listed Kp index = 5, that's a minor storm. A "6" is a moderate storm and a "7" is a strong one.
3. Geophysical Alert Message — Brief notices of coming storms
3. Download an aurora app with an alert feature — for iPhone try My Aurora Forecast or Aurora Forecast . For Android, try My Aurora Forecast & Alerts
Apps often include a live auroral oval view as well as current Kp numbers so you'll know at a glance what's happening over your head. To activate the alert feature go into settings. Several of the apps are free. Upgrades cost a couple bucks.
Keep looking up, and we'll hope together for clear skies.