Peripatetic Monday

Wandering around*, trying to find something space-related that's interesting enough to devote a post to, I stumbled across some interesting stuff.  Not the usual space news, but "close enough."  

It started with a headline on Space.com that we had a solar X-Ray flare over the weekend.  “Sun blasts out powerful X-class solar flare causing radio blackouts on Earth (video)”  I'm kind of automatically interested in things from the sun that might affect radio propagation (in either a bad or good way) and, in fact, had spent Saturday afternoon in the VHF spectrum trying to hear something new.  While my corner of the country was pretty dead, there were enough reports from scattered around the US showing the whole thing wasn't completely shut down.  

So off I went to try to find out about this radio blackout.  My first stop was the NOAA Planetary K-index website because the K-index measures the Earth's magnetic field and will show storms at a glance.  Instead, I found this:

This was puzzling.  There's no indication here of any sort of geomagnetic storm at all.  It was pretty much dead quiet.  That doesn't sound like a major storm that could cause radio blackouts.  How big was this X-class flare and when was it?  Off to SpaceweatherNews.com.

Ah ha!  The flare was just before midnight UTC on July 3 (8PM on the 2nd ET), and looks like it just barely exceeded X1.0 (in that red oval) - which is undeniably an X-class flare, but not a "serious" flare.  To get auroras visible down to Texas, say (most of which is quite a bit north of me), takes a flare of X8 to X10.  Re-reading the original source from Space.com (first link) called it X1.07.  

Still, this doesn't sound like much of a flare, so finally to the website that has offered the most information on solar activity continuously, SpaceWeather.  They provide details that fill in the picture. 

'Tis the season for fireworks. On July 2nd (2314 UT), giant sunspot AR3354 exploded, producing a long duration X1-class solar flare. NASA's Solar Dynamics Observatory (SDO) recorded the extreme ultraviolet flash:

Radiation from the flare ionized the top of Earth's atmosphere. This caused a deep shortwave radio blackout over western parts of USA and the Pacific Ocean: map. Mariners and ham radio operators may have noticed loss of signal and other propagation effects for 30+ minutes after the flare.

Those shortwave blackouts they describe are generally much more intense at lower frequencies, below 10 MHz and often not detectable without tuning below 5 MHz.  

An interesting side note to this is that while this flare lasted long enough to cause a Coronal Mass Ejection, it didn't produce one.  The SOHO satellite coronagraph images show no sign of a significant CME.  The flare's position out toward the limb would have most likely ensured that if there had been a CME, it would have missed us.  

Finally, while at SpaceWeather I noticed an interesting graphic and article that say the month of June, 2023 has posted the highest smoothed sunspot number since cycle 23 in 2002.  The highest number in 21 years.

Solar Cycle 25 wasn't expected to be this strong. When it began in Dec. 2019, forecasters believed it would be a weak cycle akin to its immediate predecessor Solar Cycle 24. If that forecast had panned out, Solar Cycle 25 would be one of the weakest solar cycles in a century.

Instead, Solar Cycle 25 has shot past Solar Cycle 24 and may be on pace to rival some of the stronger cycles of the 20th century. The last time sunspot numbers were this high, the sun was on the verge of launching the Great Halloween Storms of 2003, which included the strongest X-ray solar flare ever recorded (X45), auroras as far south as Texas, and a CME so powerful it was ultimately detected by the Voyager spacecraft at the edge of the solar system.

I've posted about this many times: the predictions of Dr. Scott McIntosh at the National Center for Atmospheric Research (NCAR) and his research partner Bob Leamon of the U. Maryland-Baltimore County started out completely opposite of the mainstream predictions for cycle 25.  While some were predicting a solar minimum and the mainstream forecast it as weak as cycle 24 (which was the weakest cycle in 100 years), McIntosh and Leamon predicted it would be stronger.  They were scoffed at and derided by colleagues but the reality of cycle 25 is much closer to McIntosh and Leamon's predictions than the others.  

Dr. McIntosh has done a presentation on the cycle progression for a ham radio group that I'm in every six months or so.  His next update within a few weeks and I should be able to post an update right after that.

*Not quite "wandering around behind the little animals" as the famous old song said, but still just web-wandering.