- 4614 - The SUN'S SOLAR CYCLES? We now know that the Sun is governed by its powerful magnetic fields, and as these fields cycle through their changes, the Sun becomes more active. Right now the Sun is at its solar maximum, a time of increased activity.
--------------------------------------------- 4614
- The SUN'S SOLAR CYCLES?
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- October 18, 2024, the Sun has reached its
Solar Maximum and it could last for one year.
For most of human history, the Sun appeared stable going about its
business fusing hydrogen into helium beyond our awareness and helping Earth
remain habitable. But in our modern technological age, that facade fell away.
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- Solar Maximum is a phase of the cycle, our
star is now exhibiting maximum activity. The Sun’s intense magnetic fields
produce more sunspots and solar flares than at any other time in its 11-year cycle.
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- The Solar Maximum is all based on the Sun’s
magnetic fields. These fields are measured in Gauss units, which describe
magnetic flux density. The Sun’s poles measure about 1 to 2 gauss, but sunspots
are much higher at about 3,000 gauss. (Earth is only 0.25 to 0.65 gauss at its
surface.) Since the magnetic field is so much stronger where sunspots appear,
they inhibit convective heating from deeper inside the Sun. As a result,
sunspots appear as dark patches.
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- Sunspots are visual indicators of the Sun’s
11-year cycle. During solar maximum, the
number of sunspots, and therefore, the amount of solar activity, increases. This increase in activity provides an
opportunity to learn about our closest star, but, also causes real effects at Earth and
throughout our solar system.
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- In May 2024, the Sun launched multiple CMEs.
As the magnetic fields and charged particles reached Earth, they triggered the
strongest geomagnetic storm in 200 decades. These created colorful aurorae that
were visible much further from the poles than usual. These aurorae were likely among the
strongest displays in the last 500 years.
-
- Scientists know the Sun is at its solar
maximum. But it lasts for an entire year. They won’t know when its activity
peaks until after they’ve watched it for months and its activity has declined.
-
- Each cycle is different, making it
difficult to label peak solar activity. Different peaks have different
durations and have higher or lower peaks than others. Understanding the Sun’s cycle is important
because it creates space weather.
-
- During solar maximum, the increased
sunspots and flares also mean more coronal mass ejections (CMEs.) CMEs can
strike Earth, and when they do, they can trigger aurorae and cause geomagnetic
storms. CMEs, which are blobs of hot plasma, can also affect satellites,
communications, and even electrical grids.
-
- During the solar maximum, the Sun produces
an average of three CMEs every day, while it drops to one CME every five days
during the solar minimum. The CMEs’ effect on satellites causes the most
concern. In 2003, satellites experienced 70 different types of failures. The
failures ranged from erroneous signals in a satellite’s electronics to the
destruction of electrical components. The solar storm that occurred in 2003 was
deemed responsible for 46 of those 70 failures.
-
- CMEs are also a hazard for astronauts
orbiting Earth. The increased radiation poses a health risk, and during storms,
astronauts seek safety in the most shielded part of the ISS, Russia’s Service
Module.
-
- Galileo and other astronomers noticed
sunspots hundreds of years ago but didn’t know exactly what they were. In a
1612 pamphlet titled “Letters on Sunspots,” Galileo wrote ‘The sun, turning on
its axis, carries them around without necessarily showing us the same spots, or
in the same order, or having the same shape.’ This contrasted with others’
views on the spots, some of which suggested they were natural satellites of the
Sun.
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- We’ve known about the Sun’s magnetic fields
for 200 hundred years, though at first, scientists didn’t know the magnetism
was coming from the Sun. In 1724, an English geophysicist noticed that his
compass was behaving strangely and was deflected from magnetic north throughout
the day. In 1882, other scientists correlated these magnetic effects with
increased sunspots.
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- In recent decades, we’ve learned much more
about our stellar companion thanks to spacecraft dedicated to studying it. NASA
and the ESA launched the Solar and Heliospheric Observatory (SOHO) in 1995, and
NASA launched the Solar Dynamics Observatory (SDO) in 2010. In 2011, we got our
first 360-degree view of the Sun thanks to NASA’s two Solar TErrestrial
RElations Observatory (STEREO) spacecraft. In 2019, NASA launched the Parker
Solar Probe, which also happens to be humanity’s fastest spacecraft.
-
- Our understanding of the Sun and its cycles
is far more complete now. The current cycle, Cycle 25, is the 25th one since
1755. Scientists use sunspots to track
solar cycle progress; the dark spots are associated with solar activity, often
as the origins for giant explosions—such as solar flares or coronal mass
ejections—that can spew light, energy, and solar material out into space.
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- Solar Cycle 25 sunspot activity has
slightly exceeded expectations. The most
powerful flare so far in Cycle 25 was on October 3rd, when the Sun emitted an
X9 class flare. But scientists anticipate more flares and activity to come.
There can be significantly powerful storms even in the cycle’s declining phase,
though they’re not as common.
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- On October 3, 2024, the Sun emitted a
strong solar flare. This solar flare
is the largest of Solar Cycle 25 and is classified as an X9.0 flare. X-class
denotes the most intense flares, while the number provides more information
about its strength.
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- The Sun’s 11-year cycle is just one of its
cycles, nested in larger cycles. The “Gleissberg cycle” lasts between 80 to 90
years and modulates the 11-year cycle. The “de Vries cycle” or “Suess cycle”
lasts between 200 and 210 years, and the “Hallstatt cycle” lasts about 2,300
years. Both of these cycles contribute to long-term solar variation.
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- However, even with all we know about the
Sun, there are big gaps in our knowledge. The Sun’s magnetic poles switch
during the 11-year cycle, and scientists aren’t sure why. There’s a lot more to learn about the Sun,
but we won’t run out of time to study it any time soon. It’s in the middle of
its 10-billion-year lifetime and will be a main-sequence star for another five
billion years.
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-
November 20, 2024 The
SUN'S SOLAR CYCLES? 4614
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--------------------- --- Wednesday, November 20,
2024
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