Earth might get roasted just like today’s Thanksgiving turkey but not till after dinner, when we’re all ready for a nap. That’s right. A busy swarm of protons and electrons from a pair of M-class flares in sunspot group 1618 appears to be headed our way. The group has been rapidly expanding and growing magnetically more complex since it rounded the sun’s limb about a week ago. Twisted magnetic fields within 1618 ignited two strong flares yesterday including the M3 pictured above that hurled material in an earthward direction at more than 1,100 miles per second.
Short movie of the Nov. 21 M3-class flare in active region 1618
Space weather forecasters predict quiet for today, but as early as tonight we might see the start of minor auroras with a chance for major storms through Friday as 1618’s ejecta puts the squeeze on Earth’s magnetosphere. That could mean anything from auroras in the Arctic regions only to their expansion well into southern Canada and the northern U.S. Sometimes these forecasts hit the mark, other times nothing much happens except in the far north. I’ll be monitoring and send off an alert if warranted.
The moon will be in gibbous phase the next few nights and brighten the sky a fair amount especially along the horizon. Be aware of that when you’re searching for those telltale aurora glows in the northern sky.
Coincidentally, NASA’s Earth Observatory site featured a pair of sun photos this week taken by the twin STEREO (Solar TErrestrial RElations Observatory) spacecraft. Each spacecraft is in its own orbit similar to Earth’s, but STEREO-B (behind) follows about 90 degrees behind the Earth and STEREO-A (ahead) about 90 degrees ahead. Between these two sets of eyes in space, we can see all the way around the sun anytime we want. No longer do astronomers have to wait for days for the solar backside to revolve into view. Revolution is so 20th century.
On October 14, STEREO-B took a photo of a dark linear feature on the sun in UV light called a filament. Using a sophisticated solar filter, amateur astronomers can see filaments hovering above the bright surface of the sun most days of the week. STEREO-A, which was more than 90 degrees ahead of B at the time, saw the filament in profile as a brilliant red prominence against the blackness of space.
Both are pictures of the identical feature seen from different perspectives at the same time. What is a filament / prominence? Hot, electrified hydrogen gas suspended in the sun’s atmosphere by magnetic fields. Every so often, those fields become unstable and fling a filament into space at high speed. If Earth’s in the line of sight, filament material – the usual protons and electrons – can sometimes spark auroras just like solar flares.
Anyway, I thought you’d enjoy the photos. Have a great Thanksgiving!