The evening of May 7 is expected to be marked by an enormous auroral storm
Once again, a moderate to intense geomagnetic storm is predicted. The latest space weather forecast indicates that northern tier state and Canadian watchers may see aurora as soon as it becomes dark on Sunday, May 7.
At some point between 10 p.m. and 1 a.m. CDT, the storm is expected to gain enough strength to be classified as a G3 (strong). Southern Wisconsin, northern Illinois, and northern Iowa would then be able to see the aurora. We should have a decently dark viewing window, but keep in mind that the bright gibbous moon will rise at about 11:30 p.m.
In the early hours of the morning on March 23rd, well before the end of twilight, I witnessed the first columns of aurora shining over the northern sky. Perhaps this will happen again. Perhaps the predictions will fall flat. Keeping an eye out is the only way to find out. Consider going for a drive if your skies are foggy and misty like mine so that you can locate a sucker hole, as amateur astronomers call an aperture in the clouds.
Cloud tracking and finding clearer skies is a breeze when you combine the Clear Dark Sky site with the NOAA GOES-East satellite’s imagery. However, I recently came across a fantastic software called Windy.com that offers superb, real-time cloud maps 24/7. This free software is available for both the iPhone and Android and was crucial in finding a clean area of sky to view the last major aurora in my area.
To use the Satellite feature, open the app, and then click the cloud with lightning bolts in the lower right. The cloud cover is displayed on a zoomable map. Clouds have a cottony, white appearance when seen at night. Clearings in the clouds can be identified as the dark areas between the masses.
The aurora season this spring has been fantastic so far. The northern lights are most visible in the spring and fall, when solar activity is low. Several factors contribute to this phenomenon, but a recent investigation suggests that the Kelvin-Helmholtz instability is at play. Even though it’s a mouthful to say, you’ll understand what it means immediately.
When two layers of the atmosphere or two bodies of water are moving at different rates, an instability might form. Unique clouds resembling wind-tossed ocean waves are the end result when this occurs in Earth’s atmosphere. The equinoxes are times when solar waves of charged particles collide with Earth’s magnetic field, producing similar effects.
The axial tilt of the Earth is neither toward nor away from the sun during the spring and fall seasons. This orientation turns out to be optimal for promoting the birth of Kelvin-Helmholtz waves. When solar material streams hit Earth’s magnetic envelope (the magnetosphere), it generates K-H waves, which in turn accelerate electrons to high speeds and send them soaring into Earth’s upper atmosphere, where they spark auroras.
K-H waves and auroras are both significantly less common when Earth and its magnetic field are tilted away from the sun at the solstices. Scientists used data from two NASA missions—the Magnetospheric Multiscale (MMS) and the Time History of Events and Macroscale Interactions during Substorms (THEMIS)—to achieve the discovery.
Let’s cross our fingers that the weatherman has it right for Sunday night and that we both end up on that fabled land of cloudless skies.