Sunspot Appearance Marks Beginning of New Solar Cycle
- By John Borland 2008
A small sunspot appeared on the sun’s northern hemisphere on Jan. 4, heralding the beginning of a new 11-year solar cycle, researchers say.
Here on Earth, it’s not obvious what that means to our everyday life. The sun will continue to rise and set as always, or – where I’m writing from – be mostly invisible behind winter clouds.
But the solar cycle, or solar magnetic activity cycle, is one of the core phenomena driving sunspots and solar weather, which can ripple out to cause disturbances such as satellite inference here.
First observed in 1843, the solar cycle lasts on average 11.1 years, with sunspots switching magnetic polarity at the beginning of each new cycle. Technically, a full genuine cycle would last 22 years, as the polarity reverses and then comes back to its initial position, but the original 11-year designation has been kept.
Following customary usage, this is designated "Solar Cycle 24," with the first in the series being the cycle lasting from 1755 to 1766. The initial sunspot isn’t much to look at, but activity should build over the course of the cycle, say researchers who spotted the marker using the Solar and Heliospheric Observatory (SOHO) satellite:
This is just the beginning, and scientists are now eagerly awaiting the activity to follow. Solar Cycle 24 is expected to build gradually, with the number of sunspots and solar storms reaching a maximum by 2011 or
2012, although intense solar activity can occur at any time.
SOHO is a joint project of NASA and the European Space Agency.
SOHO: the new solar cycle starts with a ‘bang’ [ESA press release]
(Image: SOHO photo using extreme ultraviolet light, showing the region of the solar surface producing the new sunspot. Credit: SOHO/EIT (ESA
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