Rest of the sun over

New sunspots start a new solar cycle

This sunspot group from October 2008 is already part of the new solar cycle © NASA
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After more than two years of almost uncanny calm, the sun has now woken up again. Astronomers discovered several new sunspot groups in October 2008. With them the sun enters into a new cycle of activity.

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It was unusually quiet in recent years on our central star: no sunspots, barely solar eruptions. Good news for satellite operators, but cause for thought for some scientists. Because such a long period of inactivity is rather abnormal. But now astronomers can breathe a sigh of relief, because the sun is showing "signs of life" again.

"I think the solar minimum is behind us, " says solar researcher David Hathaway of NASA's Marshall Space Flight Center. "Last month we counted five sunspot groups, which is a real increase in solar activity." Although five may not sound like much, this is a significant turnaround after a record-breaking few sunspots and even long periods without any.

Beginning of a new solar cycle

Even more interesting, however, is the location and magnetization of the new spots. Because four of the five groups had exactly the opposite polarity as the last years. In addition, they did not originate near the equator, as is typical of stains in the final phase of a solar cycle, but in the high latitudes of the sun. For astronomers, these are clear signs that the patches belong to a new beginning solar cycle. display

The Sun's 11-year activity cycles are each characterized by a slow increase in activity to a solar maximum and then a further decline. The previous cycle had already reached its peak in 2000, astronomers had long expected the beginning of the new cycle, but it was delayed. "October was the first time sunspots of the new solar cycle 24 outnumbered those of the old cycle 23, " Hathaway said. "This is a good sign that the new cycle is finally starting."

Sunspot "shoots" Flare

The largest of the new sunspots appeared almost exactly on Halloween. Its two dark cores, connected by magnetic filaments several thousand kilometers long, are each larger than the entire earth. On November 3 and 4, "Number 1007" even triggered a whole series of solar B-class flares.

These magnetic eruptions were also felt on Earth: X-rays hit the day-side of our planet and sent waves of ionization through the atmosphere across Europe. The turbulence in the ionosphere produced inter alia disturbances in the signals of amateur radio.

Still, this is no cause for excitement: "We are still years away from the next solar maximum, " explains Hathaway. In the meantime, the sun will have more calm phases. Even in October, 20 of the 31 days rested on our central star. But after all: The beginning of a new cycle is made.

(NASA, 14.11.2008 - NPO)