A Coronal Mass Ejection

As spring begins, our thoughts often turn, if only briefly, to the sun and the welcome effect its higher angle in the sky and the lengthening hours of daylight will have on our winter-weary lives.  Soon, spring thunderstorms and warm humid air will make our crops thrive.  Plant buds will open to reveal flowers and leaves, and wildlife will hurry to raise a new generation.  We’re reminded that the sun is the source of earth’s life—and is its ongoing benefactor.

The rotation period of the sun’s outer layers, the convective zone and the visible photosphere, chromosphere, and corona, is approximately 25 earth days at the equator and as long as 36 days at the poles.  Closer to the core, the rotation period in the radiative zone is about 27 days.  Note the coronal streamers, filaments of plasma extending into space around the sun.  (Image courtesy of Large Angle Spectrometric Coronagraph Experiment/Naval Research Laboratory Solar and Heliospheric Observatory Team)

Coincidentally, there was, during the first full day of spring, an explosion of plasma from the sun—a Coronal Mass Ejection.  It happened to occur on the side of the sun currently facing away from earth, so the enormous cloud of magnetic energy won’t be affecting radio communications or electric transmission here.

Friday’s Coronal Mass Ejection can be seen in the following series of images.  To protect the camera’s sensor, the direct light of the sun was blocked by an occulter at the center of each picture.  The location of the sun’s disk is indicated by the white circle.  In this set, the ejected plasma appears as a cloud emerging from behind the left side of the shield and racing millions of miles into space.  The speed of a plasma cloud produced by a Coronal Mass Ejection varies.  When directed at earth, some can reach our planet in less than a day—others may take several days to arrive.

 

(Solar and Heliospheric Observatory/Large Angle Spectrometric Coronagraph Experiment images)

Currently though, the term “Coronal Mass Ejection” may cause one to bristle and think of concerns other than the cosmos—Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and the Wuhan flu chief among them.

A Coronal Mass Ejection?  (Centers for Disease Control image)

Well, perhaps the promise of warming weather and humid days will help assuage our anxieties.

Colds and flu are certainly more prevalent in winter than during the other seasons of the year.  Cases of these diseases begin creeping through schools and workplaces just in time for the year-end holidays.  They persist into early spring each year.  Then, as we spend more time outdoors in the sunshine and fresh air of April and May, their incidence wanes.  Soon the sneezing and coughing is mostly pollen-related and less often the result of transmitted viruses.

In addition to our liberation from buildings crowded with people, spring heat introduces another factor that is apparently responsible for subduing the rapid transmission of viruses—humidity.  February and March are typically the driest months of the year in the lower Susquehanna valley.  The air outside is cold and dry.  The air inside a heated building can be worse.

Researchers have found that viruses in aerosols produced by coughing, sneezing, breathing, and talking survive longer in drier air than in humid air.  A NIOSH and CDC funded study (Noti, et al., 2013) mechanically “coughed” aerosols containing H1N1 virus into a simulated examination room.  They discovered that “…one hour after coughing, ∼5 times more virus remains infectious at 7-23% RH (relative humidity) than at ≥43% RH.”  This is a significant discovery and may shed light on why the end of heating season and the arrival of warmer humid springtime air coincides with the end of cold and flu season.  The study’s analysis determined that “Total virus collected for 60 minutes retained 70.6-77.3% infectivity at relative humidity ≤23%, but only 14.6-22.2% at relative humidity ≥43%.”  Specifically, they found that the greatest effect of higher relative humidity occurs during the first fifteen minutes after the cough, and that virus in droplets exceeding 4μM in diameter had the most significant reduction in that time—ninety percent.

It looks like a little global warming wouldn’t hurt right now.

So remember, respect the sun—fear asteroids.

SOURCES

Burnham, Robert, Alan Dyer, Robert A. Garfinkle, Martin George, Jeff Kanipe, and David H. Levy.  2006.  The Nature Companions Practical Skywatching.  Fog City Press.  San Francisco, CA.

Noti, J.D., F. M. Blachere, C. M. McMillen, W. G. Lindsley, M. L. Kashon, D. R. Slaughter, et al.  2013.  “High Humidity Leads to Loss of Infectious Influenza Virus from Simulated Coughs”.  PLoS ONE.  8:2  e57485.  https://doi.org/10.1371/journal.pone.0057485

A Little Black Spot on the Sun Today

Was there a better place to have a look at the dark side of the moon easing across the summer sun than from the Pothole Rocks at Conewago Falls?  O.K., alright, so there must have been a venue or two with bigger crowds, grand emotions, prepared foods, and near darkness, but the pseudolunar landscape of the falls seemed like an ideal observation point for the great North American solar eclipse of 2017.

The craters of the moon right here on earth, the Pothole Rocks of Conewago Falls.

Being the only person on the entire falls had its advantages, not the least of which was the luxury of pointing the camera directly at the sun and clicking off a few shots without getting funny looks and scolding comments.  Priceless solitude.

Point that camera right at that eclipse for a nice little photograph of the big event.

If you think it looks like the above photograph was taken in a house of mirrors, then you’re pretty sharp.  You’ve got it figured out.  After getting a bad case of welder’s burns on the first day of a job at a metal fabricating shop during my teen years, I learned the value of a four dollar piece of glass.

A number 12 welder’s lens in action while viewing and photographing today’s solar eclipse.
The eclipse at 2:19 P.M. Eastern Daylight Time (18:19 U.T.C), nearly as good as it was going to get at Conewago Falls.  The lunar disc would continue to the left, leaving the top fifth of the sun “uneclipsed”.

For those of you who prefer not to look at the sun, even with protection (I heard those S.P.F. 30 sunblock eye drops were a fraud…I hope you didn’t buy any.), here is the indirect viewing method as it happened today.

The eclipse is projected into the bottom of a cavernous hole in a Pothole Rock. (Three or four people can sit inside this hole.)  The tube, lenses, and mirrors of one side of a pair of binoculars were used to focus the thin sliver of sunlight onto the diabase stone “floor”.  The optics have inverted the image.

If you were to our south in the path of totality for this eclipse, you probably noted reactions by flora and fauna.  Here, there was really not much to report.  The leaves of Partridge Pea didn’t fold for the night, birds didn’t fly away to roost, and the chorus of evening and nighttime singing insects didn’t get cranked up.  The only sensation was the reduced brightness of the sun, as if a really dark cloud was filtering the light without changing its color or eliminating shadows.  And that was the great solar eclipse of 2017.