July 31, 2017 | Henry Richter

Earth’s Magnetic Field Protects Us from Solar Sneezes

by Dr Henry Richter

CME ‘sneeze’ takes aim at Earth. Credit: SOHO/NASA

A recent article about an attribute of the Van Allen Belts and how they operate strikes me as another prime example of how the Earth and its environment are designed to allow and protect life. Every now and then, the sun sends a large coronal mass ejection (CME) toward the Earth. This is a lot of dangerously destructive plasma which is a hazard to life and to electronic devices and systems. If the CME reached an unprotected Earth, it would cause widespread damage. The article on Phys.org, “Sun eruptions hit Earth like a Sneeze‘, say scientists,” describes what would happen without protection by our magnetic field.

CMEs are huge blasts of solar plasma and magnetic fields from the sun’s atmosphere that can reach Earth in one to three days. A direct hit could have catastrophic consequences, as CMEs are capable of damaging satellites, destroying electronic devices and potentially exposing people at high altitude, such as astronauts and aviation crew and passengers, to cancer-causing radiation. They occur frequently, but predicting which ones will impact Earth and how severely is difficult.

Thankfully, the Earth glides through space in a bubble called the magnetosphere which deflects moving plasma and charged particles so that they rarely reach the surface of the Earth. Some are captured by the field lines and end up as radiation in the Van Allen belts. [See 11/09/14, “Star Trek for Real,” about how the Van Allen Belts create an impenetrable force field that prevents high-energy electrons from reaching the Earth.] New research by scientists at the University of Reading was published in Nature Scientific Reports. The ‘sneeze’ analogy appears related to this finding about CMEs:

Comparing our results with observed properties of over 400 CMEs, we show that CMEs cease to be coherent magnetohydrodynamic structures within 0.3 AU of the Sun. This suggests Earth-directed CMEs are less like billiard balls and more like dust clouds, with apparent coherence only due to similar initial conditions and quasi homogeneity of the medium through which they travel.

The Van Allen belts have a special interest to me, having played a small role in the discovery of the belts. I played a role in choosing Dr. James Van Allen’s cosmic ray Geiger counter instrument to fly in the first Explorer satellites [see 9/20/16]. We had no inkling of the possibility of particles or radiation being trapped in the earth’s magnetic field. During the 1957-1958 International Geophysical Year (IGY), I was mainly interested in getting a world-wide picture of the incidence of cosmic rays, especially over a range of magnetic field conditions. As a matter of fact, we at JPL had an IGY-approved cosmic ray experiment which we were developing on our own. However, when Sputnik jolted us awake in 1957, and the Navy Vanguard test rocket blew up on the pad, the Department of Defense approved the final design and launch of the Explorer series. We did not have a flight ready JPL instrument, but Dr. Van Allen did, and he was clever enough to have designed the bolt holes to fit either the Vanguard satellite or the Explorer satellite. So when it came time to finalize the payload, as manager of instruments for the program, I had no choice but to recommend and choose the Van Allen package.

Dr Richter at 50th Anniversary of Explorer 1 (2008) holding up model of the instrument package he designed that included the Geiger counter.

It took some time to recognize the existence of the radiation belts. The first satellite, Explorer 1 (January 31, 1958), had a simple telemetry system so we only got data when it was within range of the dozen or so tracking stations. We were puzzled early on as occasionally we got no counts from the Geiger tube detector, and this was worrisome because we did not know what was wrong. I think Dr. Van Allen had an early inkling of what was going on as the missing data periods seemed to happen in a few geographic regions. It was not until we orbited Explorer 3 on March 26 (which had a data tape recorder – giving us the full orbit) that it became really clear that the Geiger tube ran into a region of increasing counts, until it saturated and stopped giving data. The Russians had missed this because Sputnik 3, which had a cosmic ray instrument, only recorded data when it was near the Russian ground stations. Those were under the orbit at its lower points, and therefore below the radiation belts.

A direct hit could have catastrophic consequences

Now, almost 60 years later, as we learn more about the wonders of this phenomenal earth on which we ride, we find that the existence of the trapping and shielding effect of the earth’s magnetic field is just one of a myriad of features that allow life to exist and flourish here. Our Creator had to put many, many things in place to make the Earth open to support life, and in particular advanced life. It is awe inspiring to have a small glimpse into why we can exist, and to marvel at it all. Thank goodness for the creation of the Van Allen belts.


We are honored to introduce Dr Henry Richter as a contributor to Creation-Evolution Headlines. A key player at NASA/JPL in the early days of the American space program, Dr Richter (PhD in Chemistry, Physics and Electrical Engineering from Caltech) brings a perspective about science with the wisdom of years of personal involvement. His book America’s Leap Into Space: My Time at JPL and the First Explorer Satellites (2015), chronicles the beginnings of the space program based on his own records and careful research into rare NASA documents, providing unequaled glimpses into events and personnel in the early days of rocketry that only an insider can give. His next book, Spacecraft Earth: A Guide for Passengers, is due out later in 2017. For more about Dr Richter, see his Author Profile.

5th Anniversary of Explorer 1 at JPL (1963): L to R, James Van Allen, Jack Froelich, Henry Richter, Bill Pickering, Al Hibbs, John Small, Homer Joe Stewart, Bob Stevens, Walt Downhower, Casey Mohl, and Carl Linnes.

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