A bit about space physics

Next post, I want to tell you a bit about space physics, what it involves, and why it's important. Firstly, you need understand a bit about the Earth, and the sun, and how they interact. The sun provides us with the light which we need to survive. It makes it warm so we can enjoy ourselves at the beach, and there is nothing better than the suns warming rays after you have been really cold. The sun gets its energy by fusing hydrogen atoms in its core. That is what happens in a hydrogen bomb. A whole lot of radioactive particles are created in this process (stuff that are really bad for us). The sun hurls these radioactive particles out in all directions, at 400km per second (up to 800 km per second when the sun gets angry). This is called the solar wind, and the Earth is constantly bombarded by it.

The earth would be cooked, if we wernen't protected by the Earth's magnetic field. The Earth's core produces a magnetic field, similar to that created by a bar magnet. It's what makes a compass point towards (magnetic) north. The picture below shows what this magnetic field looks like.

Well, thats what the field produced by the Earth would like, if it wasn't hit by the solar wind. In reality, it looks more like this:

Notice how the field on the side of the Sun is all squashed up, and that away from the Sun it is all stretched out? This is a pretty drastic change to the magnetic field. Also, as the solar wind speed changes, such as after a solar flare where particles are shot out in much higher quantities at a much higher speed, it causes a drastic compression or expansion of the magnetic field. Faradays Law says that a changing magnetic field will induce a current in a conductor. So one consequence is that electrical currents are created in our power lines. If the current in these power lines become too great, they can cause the lines to melt. One thing which space physicists do is to monitor the Sun, trying to predict such solar flares, to warn power suppliers. One thing to look out for is the occurrence of sun spots. More sun spots means there is a higher chance of a solar flare. The power suppliers will then reduce the current in power lines, to minimise the risk of them burning out.

In 1859, the largest solar flare ever recorded hit the Earth (http://en.wikipedia.org/wiki/Solar_storm_of_1859). This caused ALL the telegraph wires in the US to melt. If this kind of thing had to hit us today, global power supply would likely be destroyed.

Not all of the solar wind is diverted by the magnetic field. Some of it penetrates past the barrier, and becomes trapped in the field. These particles then travel along the magnetic field and interact with our ionosphere and atmosphere. This is what causes Aurora (the northern and southern lights). Another effect of this is modifying radio propagation conditions (radio signals reflect off the ionosphere). Ham radio operators often keep track of solar conditions for this reason. These particles have all kinds of other effects as well (there is evidence that they even trigger lightning strokes).

As you can see, our magnetic field is incredibly important. Scientists believe that Mars was once a planet like ours, with water, and a breathable atmosphere, but when its magnetic field died, the solar wind began to erode away its atmosphere. This may sound familiar if you have seen the movie, "The Core".

This post was just a heads up, hopefully alerting you to the hazards of our closest star!