Wednesday, January 16, 2008

See Spot Shine

Astronomers are celebrating the beginning of Solar Cycle 24: the beautiful beginning of the switch of the sun’s magnetic polarity that creates a tangle of magnetic field lines around the sun, and wreaks havoc on cell phones, power grids, GPS and ATM’s.

Image: This image obtained by SOHO’s EIT instrument, was taken in extreme ultraviolet light. It shows the area of the solar surface from which two ‘EIT waves,’ a kind of solar storm that blasts out from an active region across a portion of the Sun’s surface, were originated on 6 and 7 January 2008. This area is the sunspot whose appearing marked the start of the new solar cycle (‘Cycle 24’) on 4 January 2008. Photo: © SOHO/EIT (ESA and NASA)

Satellite based technology may see some severe consequences around 2011 if this turns out to be an intense solar cycle. In addition, scientists really have no way of preventing the problems that the sun’s magnetic field could cause. The cycle could cause major problems for GPS systems, and in cases where extreme accuracy from those systems is crucial, we may just have to wait it out.

Astronomers identified the beginning of the sun cycle because of the appearance of a very special sunspot. Sunspots, which are fairly common, are like bottle caps over areas of intense magnetic fields. When the field gets all built up, it bursts out of the surface through the sun spot. Scientists are able to determine the polarity of each sunspot, and when a sunspot appears with the reverse polarity of its buddies, we know the new sun cycle has begun.

Scientists are still split on just how bad this particular cycle will be. Like the seasons, the solar cycles occur in a regular pattern: lasting, on average, 11.1 years, with a possible range of 2-3 years. But their severity is debatable. Scientists have been observing solar cycles for hundreds of years, but we have only been monitoring their intensity of since the 1970’s, so they still haven’t been able to observe much in the way of different trends from cycle to cycle.

When the sun begins a new cycle that means its magnetic field is switching polarity. Changing polarity is nothing more than changing the plus side of a magnet to a minus side, like switching the side that attract metal and the side that repels it. Magnets exist because of because of the same phenomena as electricity (hence, ELECTROMAGNETISM!), so there is literally a switch in the direction that electrons flow.

The magnetic fields of the Earth and the sun are created by magnetic charges running through the core of the spheres: like a long, rectangular magnet put through the middle of a bowling ball. The sun’s magnetic field, during low cycle periods, is about as powerful as a refrigerator magnet, which is 100 times as strong as the Earth’s. Still, that’s a pretty big magnet. During the peak of the solar cycle, the entire magnet actually becomes much stronger than it is during the normal season.

Magnetic field lines from the sun can severely damage a planet, as they have done to Mercury, which is now lacking much of an atmosphere. But Earth is protected by its own magnetic field. During the peak of solar cycles, the change in polarity of the sun’s magnetic field can lead to a jumble of magnetic field lines, and solar winds can carry the effects of the magnetic field far out into the solar system.

Image: The magnetosphere shields the surface of the Earth from the charged particles of the solar wind. It is compressed on the day (Sun) side due to the force of the arriving particles, and extended on the night side. (Image not to scale.)

It’s been theorized by a few scientists that the Earth’s magnetic field changes as well, but over much, much longer periods of time; somewhere on the scale of tens of thousands to millions of years.

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