Solar Science

A blog of solar physics

Archive for December 2007

Is a New Solar Cycle beginning? Er, no. Not yet.

Much excitement from NASA, as the long delayed arrival of Solar Cycle 24 was announced:

Dec. 14, 2007: The solar physics community is abuzz this week. No, there haven’t been any great eruptions or solar storms. The source of the excitement is a modest knot of magnetism that popped over the sun’s eastern limb on Dec. 11th, pictured below in a pair of images from the orbiting Solar and Heliospheric Observatory (SOHO).

It may not look like much, but “this patch of magnetism could be a sign of the next solar cycle,” says solar physicist David Hathaway of the Marshall Space Flight Center.

Yeees, go on…

“New solar cycles always begin with a high-latitude, reversed polarity sunspot,” explains Hathaway. “Reversed polarity ” means a sunspot with opposite magnetic polarity compared to sunspots from the previous solar cycle. “High-latitude” refers to the sun’s grid of latitude and longitude. Old cycle spots congregate near the sun’s equator. New cycle spots appear higher, around 25 or 30 degrees latitude.

OK, got that. Now we have a sunspot with reversed polarity compared to solar cycle 23?

The region that appeared on Dec. 11th fits both these criteria. It is high latitude (24 degrees N) and magnetically reversed. Just one problem: There is no sunspot. So far the region is just a bright knot of magnetic fields. If, however, these fields coalesce into a dark sunspot, scientists are ready to announce that Solar Cycle 24 has officially begun.

And did this coalesce into a sunspot? No. The Sun remains stubbornly blank although there was a fair sized SC23 spot for several days that followed.There appears to be indications of a large sunspot on the far side of the Sun but that too is right on the equator and probably isn’t polarity reversed from SC23.

This isn’t the first time that a sunspot appeared to herald the next solar cycle that failed to materialize. There was another which appeared in late 2006 that got people excited for literally hours when it appeared and disappeared.

Hathaway, it must be remembered, was one of a team who predicted a very strong SC24, at least as strong as the previous one. I think the tension may be getting to him.

I think its OK to actually wait for at least a couple of magnetically reversed sunspots to appear at high latitudes before announcing the Coming of the next Solar Cycle. Whatever happens, SC24 will be late.

Written by John A

December 22, 2007 at 10:46 am

Posted in Solar Cycle 24

Tagged with , , ,