Auroras on Halloween? I can’t think of a better fit than the spooky quavering of northern lights. I’m happy to report there’s a real possibility that skywatchers in the northern U.S. and southern Canada might share their treat or treating with an ominous green arc hanging over the northern horizon.
Space weather experts are forecasting a 20 percent chance of minor geomagnetic storms and accompanying auroras for mid-latitudes through tomorrow night. Northern lights were expected this past weekend from the combined effects of several flares. The continuing parade of large sunspot groups and their associated solar flares have sent several particle blasts in our direction. None ever found a way past Earth’s magnetic defenses to spark a display of northern lights.
Let’s hope that changes on Halloween. That’s when the effects of a M4-class (medium-sized) flare from sunspot region 1882 will arrive. Clouds of high-speed subatomic particles and tangled magnetic fields lofted into space from the explosion are on the way; be on the lookout tonight and tomorrow night. All the aurora indicators have been very low the past week, but I noticed today that the Kp index has been ticking up, a good sign.
Comet Lovejoy, now visible in binoculars in the morning sky, has recently grown a narrow tail of fluorescing gas called an ion tail. Like a windsock, an ion tails wiggles and warps according to changes in speed and intensity in the wind of particles released by the sun.
All those recent coronal mass ejections sent waves of particles across the solar system, some of which flowed right across the comet and may have caused a twist in its tail recorded by amateur astronomers earlier this week. The animation, compiled by Alan Watson from images taken by NASA’s STEREO sun-watching spacecraft, show the waves very clearly.
For more on finding Comet Lovejoy and the three other bright-ish comets in the morning sky, please see my article Four Comets Haunt the Halloween Dawn on Universe Today. Detailed maps are included.