Those of us who live here in Alaska have probably seen the Aurora Borealis, or Northern Lights, at least once or twice (well, those of us who don’t live someplace where it’s cloudy all the time, like Juneau). The good news is that we may get another chance to do so this week, due to a solar storm that occurred on June 21, the summer solstice. The storm triggered a powerful explosion on the sun, called a coronal mass ejection, which sent a vast wave of solar particles directly at the earth at a speed of 1.4 million miles per hour, which means that they should be getting to vicinity of the earth just about now. The good news is that these particles are so small that you would need a piece of scientific equipment the size of a house to detect them, so there is no need to call Bruce Willis. Also, since the earth has a magnetic field that surrounds it, nearly all of these particles will get deflected before they reach the earth’s surface. Hopefully, this will create the cosmic light show called the aurora, which results from the interaction of these particles and the oxygen and nitrogen atoms in the atmosphere, which causes these atoms to become ionized and emit light (see picture above).
This also tells us something about the composition of the earth’s atmosphere, and in fact scientists used to send rockets up into the aurora in order to find out more about the interaction between these solar particles and the atmosphere (this is still done). This can also tell us something about the processes which are going on deep within the sun, which would be impossible to do otherwise because the temperatures are in the range of millions of degrees. The solar flare was detected by NASA’s SOHO satellite, which stands for Solar and Heliospheric Observatory, which is jointly operated with the European Space Agency and has been in orbit since 2004.
Actually, solar flares have the potential to cause serious damage to the communications and electronic infrastructure of planet Earth if they are strong enough, and can pose a serious danger to astronauts in space, because they aren’t protected by the Earth’s atmosphere, like we are. In fact, some scientists believe that high solar activity in the past may have played a part in the extinction of some species. Fortunately this was only a class C flare, which is the weakest kind (class X is the strongest), so hopefully, the only effect that should occur is a pretty show in the sky. That is, if the clouds ever go away.