Resurgent sun peaks for second time
By Richard Stenger
(CNN) -- Hurling great heaps of energy into space at a brisk pace, the sun has likely entered a second phase of major intensity during an 11-year cycle of activity.
When the sun reached solar maximum in the summer of 2000, it boasted frequent, powerful eruptions and thick packs of electromagnetic storms known as sunspots.
It calmed down over the ensuing months, but vigorously boiled back into life and by the beginning of 2002 had reached a second peak, NASA scientists said.
"Sunspot counts peaked in 2000 some months earlier than we expected," said David Hathaway, a solar physicist at the NASA Marshall Space Flight Center. Considering recent developments, "the current solar cycle appears to be double-peaked," he said.
In recent weeks, our reawakened parent star has become riddled with more sunspots, which are associated with potent radiation storms known as coronal mass ejections and solar flares that can disrupt the electrical environment around our planet.
Days ago, a radiation gust that probably originated near one particularly noticeable sunspot crashed into our upper atmosphere, setting off impressive light displays known as auroras in northern and southern latitudes.
"They never ceases to amaze me. And it is always worth getting up in the middle of the night for," said Mark Simpson of Calgary, Canada, co-creator of the Aurora Detection and Early Warning System, which offers e-mail alerts about aurora displays in different regions.
"The display this week was no exception. It started off to the north but as the evening progressed, it filled the whole sky. My wife and I find nothing as beautiful as seeing these displays. Any picture or video is of poor comparison to the real thing."
The first peak and slightly smaller second encore represent the apex of an 11-year cycle of solar activity. During the maximum phase, the sun's magnetic field becomes increasingly unstable and flips, according to NASA.
Besides bathing the sky with colorful lights, solar radiation bursts can disrupt radio communications, damage satellites and knock out power grids.
To understand better how solar weather affects our planet, numerous satellites keep their eyes focused on the sun. One such spacecraft, the High Energy Solar Spectroscopic Imager, or HESSI, joined their ranks in space on Tuesday.
When the NASA orbiter soon becomes operational, it will create the first high-fidelity color films of solar flares, the most powerful explosions in the solar system.
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NASA's Marshall Space Flight Center
High Energy Solar Spectroscopic Imager
Solar and Heliospheric Observatory
Auroral Detection and Early Warning System
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