JUST WHAT IS GOING ON UP THERE?
There have been quite a few stories in the press over the last few weeks about things happening with our favourite star, the Sun. Many of these stories use sensationalist language like “satellites knocked back to Earth” and “giant solar storm will roast us all” so I thought I had better explain just what is going on.
The first thing to understand is that the Sun is not a steady unchanging star, like everything in nature, it's changing all the time, we call it a variable star. Fortunately for us it only varies by about 0.1 %, if it was much more Earth would be a very unpleasant place for humans.
A major part of this constant change is what's called the solar cycle, a period of time over which the Sun goes through a rise and fall in how much activity is going on up there. Actually, there are several different cycles some of which overlap, these include a rise and fall in the number of sunspots, a complete reversal of the Sun’s magnetic field and a rise in the number of solar flares. All these things are linked but an explanation involves quite a bit of nuclear physics, and this isn't the place for all that.
What is concerning the newspapers most is the number of solar flares and CMEs or coronal mass ejections. Despite what newspapers say, these are not the same thing at all, although they are linked. A solar flare isn't a real concern to us, but a CME is a different matter, so just what is it? Simply put it's a vast cloud of solar plasma, highly magnetic and full of protons and electrons that will take up to 18 hours to get from the Sun to Earth. It's these particles that can and do cause havoc for us. The most intensive recorded solar storm was called the Carrington event in 1859, at the dawn of our electrical age. It almost destroyed many telegraph systems, even setting fire to some telegraph stations. Society has moved on since then and almost everything now is vulnerable to these events. Naturally engineers are well aware of the dangers, and will do what they can to design protection, but that makes things more expensive, so many things like electrical transformers have to take their chances.
That's the bad news, the good news is that we would have to be unlucky to be hit by a dangerous CME. The Sun is a vast globe, we are a tiny planet so the chances of a big CME firing off at just the right time, in just the right direction to hit us are small. But sooner or later............
This month’s picture was taken a short time ago by Ron Giddy, one of our members.
That cloud leaving the Sun, is much bigger than the Earth.
Charles Oates, Vega Baja Astronomy Group.