Boo! Ghostly auroras possible on Halloween

A farewell X2-class flare from big sunspot region 1875 as it departed the sun’s face late Tuesday afternoon Oct. 29. Although it blasted out a massive cloud of electrons and protons (see below), the material doesn’t appear to be directed toward Earth. Credit: NASA

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.

Aftermath of the X2 flare from sunspot region 1875 – a massive burst of particles lifts off the sun to the right. Photo made with a coronagraph, which blocks the sun so astronomers can study the sun’s corona or atmosphere. Credit: NASA / SOHO

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.

Waves of CME (coronal mass ejection) material sweep past Comet Lovejoy earlier this week in an animation of STEREO space probe images compiled by Alan Watson.

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.

Kinking and bending in the ion tail of Comet Lovejoy seen here on Oct. 29 may be result of the passage of waves of solar particles entwined with magnetic fields. Credit: Gerald Rhemann

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.

2 thoughts on “Boo! Ghostly auroras possible on Halloween

  1. Several days of clouds and rain. If it does not clear off tonight, I am going to have to wait till Monday to look for the comet quartet.

  2. Less than 700 hours to go for ISON to reach it’s hottest temp. I am encouraged by it’s present performance for 2 reasons. First, it seems to be intact meaning that it is not splintering and burning up. While the dimmer than normal may seem a bad sign. To me that is a good sign. If it is brighter than normal, it would possibly mean that it is already burning itself out. Being dimmer than normal may mean that it’s components have not yet been very affected by the Sun. It must still be fairly cool, still over 90 million miles from the Sun. I have read that at perihelion it could be 5000 degrees. By then these components that it is made of will be melting for sure and then the comet could blaze in all of it’s glory. And I am not worried about Lovejoy being brighter than normal. It will not probably get close enough to the Sun to break up or vaporize away.

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