Wednesday, August 7, 2013

The Magnetic Flip

Recent news have been mentioning the upcoming flip of the Sun's magnetic poles.
What is a magnetic flip and how exactly does it happen?

Our sun transfers energy from the core to the radiative zone, and then to the convective zone, and out to the photosphere (the visible disc of the sun). The vertical motion of the plasma in the convective layer causes the magnetic field lines to twist into flux tubes. When the flux tube increases its energy it then rises as an active region. The magnetic field lines arch from these areas from one polarity (+) to the other (-). The magnetic polarities of each active region is similar but reversed in each hemisphere.

Now, the Sun has a solar cycle described as a period of very few magnetic activity followed by increasing activity over a time of 11 years. The year 2013 is the solar maxima which signifies the end of the current solar cycle. After the 11-year cycle, the magnetic polarities of the active regions suddenly reverse and will remain as such for another 11-year cycle. So a period of 22-years make up one magnetic cycle of the Sun.

The Sun's northern hemisphere has already reversed its polarity as you can notice in a period of almost 0 activity for the month of July (see absence of AR regions in the Northern part for the month of July in these solar images). The southern hemisphere is following suit.

So what does a magnetic flip do?
Well, the Sun has a region of influence called the heliosphere which reaches out to the ends of the solar system. We monitor this sphere as what we call space weather. Charged particles (cosmic rays, plasma, etc.) in space travel with respect to the magnetic field lines of the Sun and of the planets. When the magnetic orientation of the Sun flips then so does the orientation of these charged particles. The sudden switch causes a storm in the space weather.

Solar Observation Program
Department of Earth and Space Sciences
Rizal Technological University

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