Just a few days ago, our planet was hit by the most powerful geomagnetic storms in the last seven years. As the scientists of the National Oceanic and Atmospheric Administration’s Space Weather Prediction Center had predicted, a solar flare occurred on January 23, 2012; it sent out a cloud of charged particles from the sun’s atmosphere out into space. This coronal mass ejection (CME) was so big that it unleashed a powerful geomagnetic storm in our atmosphere, affecting our communication networks, causing power outages and disrupting air traffic schedules. Sky-gazers had an amazing time as they watched spectacular auroras produced by the flare. Take a look at some beautiful aurora pictures here.
Why does a small flare on the surface of the Sun have such a tremendous impact on earth?
Solar flares explained
On the surface of the Sun, there are prominences or large magnetic loops. When the prominences or coronal loops touch each other, they set off explosions and release huge amounts of energy. This energy release is seen as sudden and intense variation in brightness on the surface of the Sun. We call this a solar flare.
A solar flare can generate energy that is equivalent to several hydrogen bombs exploding at the same time. However, only a fraction of that energy reaches the earth. Solar flares release a barrage of gas, ultraviolet light, x-rays, electrons and visible light. As the particles and radiation reach the earth’s atmosphere, they interact with the magnetic fields at the poles to create beautiful auroras.
The effects of the latest solar flare were moderate, though it caused airlines to reroute planes from polar areas to areas where radio communication remained unaffected. If a serious solar flare occurs, satellites may get damaged and astronauts aboard space ships may get radiation poisoning.
Solar flares were first observed by Richard Christopher Carrington in 1859. Similar stellar flares occur on other stars too. Small solar flares occur on a regular basis. The frequency varies from several per day to less than one in a week. Large flares are relatively rare. The Sun undergoes high and low cycles of electromagnetic activity every 11 years. Right now we are at the beginning of a peak activity or a solar maximum.
Solar flares and radioactive decay
It is easy enough to understand that the particles ejected from the surface of the sun can affect earth’s magnetic field and cause disruptions in radio communications and affect our satellites. But strangely enough, it seems to affect the rate of radioactive decay of carbon isotopes on earth.
This is fascinating because scientists consider the rate of radioactive decay to be a constant. In fact, we use the steady rate of decay of Carbon-14 to date fossils and ancient artifacts accurately.
In 2006, physicists Ephraim Fischbach and Jere Jenkins, Purdue University, discovered that the rate of decay of certain isotopes seemed to vary seasonally. Though at the time the discrepancy was chalked up to experimental error, a solar flare that occurred in Dec 13, 2006 provided a vital clue. Jenkins found that the decay rate of manganese-54 decreased slightly during the flare. The drop had started about a day before the flare occurred.
This meant that something from the Sun had traveled to Earth before the actual flare happened. The physicists surmised that solar neutrinos were the probable reason behind this decay rate variation. Neutrinos have no electric charge and almost no mass, so they interact only with weak nuclear force, which is what causes radioactive decay. If the mystery particle that causes this variation is not a neutrino, it would have to be a particle which is not yet detected.
By: Nisha Salim
- Todays solar flare… (ion360.wordpress.com)
- Solar-Storm-Fueled Auroras Make for Awesome Backyard Photography (wired.com)
- Sun Unleashes Strongest Flare Yet of 2012 (space.com)
- Why you should be excited for giant solar flares (dvice.com)