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Tech Talk

  1. The Sun Flips Its Magnetism.

  2. Bose Theory Slows Down Light.

  3. Your Brain Circuits. Coming Soon On A Chip Near You.

  4. Electricity from Space.

  5. Brain Waves Move Objects.

  6. Burning Waters in Sunless Seas.

  7. For other columns in Hindustan Times, click here.

The Sun Flips Its Magnetism.

If nine of your own children danced around you forever as you just hang out there, burning fiercely for millions of years, would you not flip it? I would. Therefore, it should come as no surprise to you that the Sun has also flipped it. Just like that. Yes, barely a few weeks ago around the middle of February, the Sun's magnetic field flipped. The star's magnetic north pole, which is in its northern hemisphere, now points to the south. Unusual as it may sounds, the Sun actually reverses its polarity with clockwork accuracy every 11 years.

The few years preceding each flip is marked by heightened magnetic activity, when intense magnetic loops, hundreds of time stronger than the Sun's magnetic field start dotting the star's surface. Such magnetic spots are called Sunspots. A bizarre phenomenon occurs as more and more whirlpools of magnetic energy dot the Sun's surface. Strange rivers of magnetism on the Sun's surface carry the heightened magnetism from the Sunspots to the opposite and attracting magnetic poles of the Sun. As more of the opposite magnetism accumulates at the poles, the original magnetic poles steadily weaken until, well, they just flip. The whole process then starts afresh. So for the next 11 years, the Sun's magnetic north will stay in the southern hemisphere until it flips again in the year 2012.

How will this dramatic magnetic phenomenon effect the Sun's wonderful family of nine planet, including our own? According to NASA, the Sun's magnetic field is about as strong as a refrigerator or a child's toy magnet, which is about 50 gauss. A gauss is a unit of magnetic intensity. The Earth's magnetic field is 100 times weaker than the Sun's. However, the Sun's magnetic field envelops the entire solar system in a bubble that scientists call the 'heliosphere.' The heliosphere extends a little beyond the solar system's furthest planet, Pluto. "Changes in the Sun's magnetic field are carried outward through the heliosphere by the solar wind," explains Steve Suess, a solar physicist at the Marshall Space Flight Center. "It takes about a year for disturbances to propagate all the way from the Sun to the outer bounds of the heliosphere."

The impact of the field-reversal on the bubble that envelops our solar system is complicated to study. This is because the Sun also spins on its axis, much like the Earth, once every 27 days. So solar magnetic fields corkscrew and spiral outward, somewhat like the string from a child's spinning top. The added impact of Sunspots in this magnetic soup leads to a highly complex phenomenon of energy that cushions out into the heliosphere. You need not worry though. This magnetic reversal does not lead to cataclysms and dramatic upheavals for life on Earth. After all, we have been surviving these flips every 11 years through hundreds of centuries. Towards the end of this year, a unique spacecraft called Ulysses will fly very close over the north pole of the Sun. Ulysses is a joint venture between NASA and the European Space Agency. It was launched in 1990 to observe the solar system from very high above, and every six years it travels rather near the Sun's poles. Scientists hope the data received during this loop will offer several new insights into the Sun's magnetism.

Incidentally, our beloved Earth also flips its magnetic polarity. The time-period is less regular, with intervals 5 thousand years to 50 millions years apart. The last reversal happened 7,40,000 years ago, and some scientists feel the next reversal is overdue. Nobody knows when, and what would be its impact on life on Earth. The next column in this series will cover what may happen when our Earth flips it.

23 May 2003 © niyam bhushan

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