Solar Activity Program
I have already posted a bit on the variation of solar activity during a solar cycle and on solar storms. The Bulletin article on the Solar Activity Program starts by noting that variations of the sun's activity had been recognized since shortly after the invention of the telescope in the early 1600s, when Galileo developed an improved telescope to enable him to discover and sketch sunspots.
For the IGY, principal goals for this program included warnings of expected geophysical effects of solar activity on terrestrial phenomena, and collecting comprehensive physical measurements of all measurable solar phenomena. Ten solar observatories in the U.S. were focused on these goals.
Solar flares were among the ten or so solar phenomena affecting the Earth that were observed. Observations at intervals of three minutes or less were taken at several stations, including the Mount Wilson Observatory (California) and the Sacramento Peak Sunspot Solar Observatory (actually located in Sunspot, New Mexico) which still exist. Today I purchased a cover postmarked from the location of the Sunspot Observatory, in Sunset, NM, on March 22, 1983 (25 years after the IGY), the date of launch of STS-3, the third mission for the Space Shuttle Columbia. It turned out that this shuttle was forced to land eight days later at White Sands, NM (only 50 miles southwest of Sacramento Peak), the only shuttle to do so, due to flooding at its originally planned landing site, Edwards Air Force Base.
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| My new cover (US 224) postmarked from Sunspot, NM, on launch date of the Space Shuttle (eBay image of the cover) |
Among other solar measurements to be made, the Mount Wilson and Palomar Mountain Observatories were to map out the magnetic field of the solar disk on a daily basis using the Zeeman effect, whereby a magnetic fields splits spectral lines of the solar light emissions. Pieter Zeeman won the Nobel Prize in 1902 for discovering this effect.
Cosmic Ray Program
The second article in this issue of IGY Bulletin is on the Cosmic Ray Program. Cosmic rays are actually highly energetic particles originating in space, from supernovas in other galaxies, and from our Sun. In a process called spallation, primary cosmic rays interact with molecules in Earth's atmosphere to produce a variety of secondary cosmic rays, i.e., different kinds of particles. These various particles require different methods to indirectly detect cosmic rays via their by-products.
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| By-products of cosmic rays interacting with air molecules |
The Bulletin article states that a number of projects (outlined in more detail than you would want to know) were to continuously measure cosmic ray intensity via secondary neutrons and mesons (i.e., pions/p-mesons and kaons/k-mesons) at the ground surface and also at elevations using balloons. These would enable the determination of cosmic ray particles' composition, masses, charges, and their changes over time. Measurements at different latitudes were made to consider the relation between the latitudinally variable geomagnetic field and cosmic ray intensities.
Among the scientific investigators mentioned in the article is S.F. Singer, then at the University of Maryland (my father had a barber shop in College Park at that time, a couple of miles from where we lived, so maybe he cut Singer's hair). Singer was present at a 1950 dinner party hosted by James Van Allen where the idea for the IGY was first hatched. He later became known as Fred Singer, a science contrarian (which I think is a generous term) "who sought to denigrate other scientists who warned the public about secondhand smoke, greenhouse gas emissions, acid rain and the dangers of a steadily warming climate" (Washington Post).
My personal research connection with cosmic rays occurred in graduate school, when I was a research assistant with Dr. Paul Damon, one of the great mentors of my life. Among Paul's many interests was radiocarbon geophysics and the calibration of the radiocarbon timescale. Radiocarbon (i.e., radioactive carbon), aka carbon-14, is a radioactive isotope of carbon produced in our atmosphere as a spallation product of the interaction of cosmic rays with nitrogen, the most abundant element in our atmosphere. As the Earth's magnetic field changes strength over time (fodder for a future post), cosmic ray fluxes into the atmosphere change as well since charged cosmic ray particles are affected by magnetic fields. This changes the rate of radiocarbon production (e.g., Damon and Sternberg, 1989), which in turn affects carbon-14 dating; this means that carbon-14 dates have to be corrected for this effect.
To close, here is a contemporary tutorial and update on cosmic rays from Dr. Veronica Bindi, physics professor at the University of Hawaii:
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