The Sun is on the verge of a significant event: a reversal of the magnetic field.
This event occurs roughly every 11 years and marks an important stage in human history. solar cycle. The change in polarity indicates the halfway point. solar maximumthe height of solar activity and the beginning of the transition towards solar minimum.
Last time SunTowards the end of 2013, the magnetic field reversed. So what causes this change in poles and is it dangerous? Let’s take an in-depth look at the reversal of the Sun’s magnetic field and examine its effects on the sun. Soil.
Relating to: How a giant sunspot unleashed solar storms that birthed global auroras that dazzled us all.
To understand magnetic field reversal, it is important to first become familiar with the solar cycle. This approximately 11-year cycle of solar activity is driven by the sun’s magnetic field and is indicated by its frequency and intensity. sunspots can be seen on the surface. The height of solar activity during a particular solar cycle is known as the solar maximum, and current forecasts predict that it will occur between: end of 2024 and early 2026.
However, there is another very important, although less well-known, cycle that encompasses two 11-year solar cycles. This magnetic cycle, known as the halo cycle, lasts approximately 22 years, during which the Sun’s magnetic field reverses and then returns to its original state. Ryan FrenchThe solar astrophysicist and Space.com contributing writer told Space.com:
During solar minimum, the sun’s magnetic field is close to a dipole, with a north pole and a south pole. Earth’s magnetic field. However, as it moves toward solar maximum, “the sun’s magnetic field becomes more complex, with no clear north-south pole distinction,” French said. When the solar maximum passed and the solar minimum reached, the sun returned to the dipole, although it was of opposite polarity.
The upcoming change in polarity will be from north to south in the Northern Hemisphere and vice versa in the Southern Hemisphere. “This would put it in a similar magnetic orientation to Earth, which has a south-pointing magnetic field in the Northern Hemisphere,” French explained.
What causes the switch in polarity?
The reversal is driven by sunspots, magnetically complex regions on the sun’s surface, and can give rise to major solar events. sunlight And coronal mass breakthroughs (CMEs) — large explosions of plasma and magnetic fields.
As sunspots emerge near the equator, they will have an orientation that matches the old magnetic field, while sunspots that form closer to the poles will have a magnetic field that matches the incoming magnetic orientation, French said. This is called Hale’s law.
“The magnetic field from the active regions moves towards the poles and eventually causes reversal,” said solar physicist Todd Hoeksema, director of the Wilcox Solar Observatory at Stanford University. I told Space.com before.
However, the exact reason behind such a shift in poles remains a mystery. “This goes into the whole [solar] “We still don’t have an internally consistent mathematical explanation for what’s happening. And until you model it, you don’t really understand it; it’s very hard to really understand it,” solar physicist Phil Scherrer of Stanford University previously told Space.com.
It really depends on where the magnetic field is coming from. “Will there be a lot of sunspots? And will the sunspots contribute to the pole’s magnetic field, or will they just kind of cancel out locally?” Hoeksema said: “We don’t know how to answer that question yet.”
How quickly does the transition occur?
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What we do know is that the change in the solar magnetic field is not instantaneous. This is a gradual transition from the dipole to the complex magnetic field to the reverse dipole over the entire 11-year solar cycle. “In short, there is no specific ‘moment’ when the Sun’s poles reverse,” French said. said. “This is not like Earth, where rotation is measured by the migration of the North/South pole.”
It usually takes a year or two to completely reverse, but it can change significantly. For example, Solar Cycle 24, which ended in December 2019, took about five years for the north polar field to reverse. National Solar Observatory.
The magnetic field change is so gradual that you won’t even notice when it happens. And no, as dramatic as it sounds, this is not a sign of impending doom. Scherrer “The world will not end tomorrow” it has been said before Space.com.
However, we will experience some side effects of the pole change.
How does the sun’s magnetic rotation affect us?
There’s no doubt that the Sun has been incredibly active lately, firing off numerous powerful solar flares and CMEs, triggering powerful geomagnetic storms on Earth, and these storms have also led to some explosions. Incredible aurora displays of recent times.
However, the increase in violence space weather It is not the direct cause of the polarity change. Instead, these events tend to occur together, Hoeksema told Space.com in 2013.
According to French, space weather is generally strongest during solar maximum, when the sun’s magnetic field is also most complex.
One side effect of the magnetic field shift is mild but primarily beneficial: It could help protect Earth from galactic attack. cosmic rays — high-energy subatomic particles that move at near the speed of light and can damage spacecraft and harm orbiting astronauts outside Earth’s protective atmosphere.
As the sun’s magnetic field changes, a “current layer” emerges, an expanding surface that spreads billions of miles from the sun’s equator. it gets very wavyProvides a better barrier against cosmic rays.
Predicting the strengths of the future solar cycle
Scientists will carefully monitor the reversal of the sun’s magnetic field and see how long it takes for it to return to its dipole configuration. If this occurs within the next few years, the next 11-year cycle will be relatively active, but if accumulation is slow the cycle will be relatively weak, like the previous Solar Cycle 24.