The sun is starting to revive again.
An international group of scientists announced Tuesday that the sun has emerged from the quieter end of its 11-year sunspot cycle and has now entered its 25th numbered cycle. (The numbering of sunspot cycles dates back to 1755.)
The researchers predicted that the next cycle would be rather quiet.
Solar scientists follow the cycle through the ebb and flow of sunspot numbers, which reflects the level of ferocity in the sun’s magnetic fields. Sunspots can emit bursts of radiation called solar flares as well as gigantic particle eruptions known as coronal mass ejections. If a gigantic coronal mass ejection hits Earth, it could overturn modern civilization, destroying satellites and inflicting blackouts across the continent.
Just as economists wait months to declare the start or end of a recession, scientists delay such claims for solar cycles because they average 13-month sunspot numbers to avoid being fooled by short-term fluctuations. activity of the sun. Nine months ago, in December, the sunspot cycle reached its calmest state.
“It has increased slowly but steadily since then,” said Lisa Upton, a solar scientist at Space Systems Research Corporation and co-chair of the Solar Cycle 25 Prediction Panel, sponsored by NASA and the National Oceanic and Atmospheric Administration.
Over the past half century, solar cycles have become progressively weaker, leading some scientists to speculate this the sun may be at the height of a long period of quiet. The latest solar maximum, with an average sunspot number of 114, was the weakest since 1928 and the fourth weakest overall.
The forecast panel predicts that activity during this solar cycle will be well below average, peaking at 115 in the number of sunspots, given or taken 10. It would be roughly the same as in the last cycle. The maximum is expected to occur in July 2025.
“If this turns out to be true, it would make cycle 25 almost identical to solar cycle 24,” said Douglas A. Biesecker of the Space Weather Prediction Center in Boulder, Colorado, the panel’s other co-chair. A very active cycle reaches a sunspot number greater than 200, he said.
Individual scientists’ predictions still vary widely, with some predicting an even quieter cycle and others predicting a rebound to higher levels. But Dr Upton and Dr Biesecker said the panel reached a consensus fairly easily, relying on models that use measurements of magnetic fields in the sun’s polar regions to infer what would happen in the coming years.
“We’ve gotten very good at modeling the evolution of polar magnetic fields,” said Dr. Upton. “This is one of the best indicators for the breadth of the next cycle and was one of the key features examined by the forecast panel.”
He said there were other indicators that this cycle would remain quiet, including a large number of spotless days during the solar minimum. But if the sunspot cycle increases faster than expected in the coming months, it will be a sign that perhaps experts have underestimated the intensity of the upcoming cycle, he said.
Even during the weakest solar cycles, the sun can set off gigantic explosions. In 2012, an eruption that rivaled the Carrington event erupted from the sun’s surface, but fortunately it wasn’t headed for Earth.
However, a calmer sun increases the odds that our planet will not be hit by a solar cataclysm in the next 11 years.